6 files changed, 478 insertions, 308 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a27e42bf3400..295cbaa0e58a 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -148,6 +148,7 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
         elf_addr_t *elf_info;
         int ei_index = 0;
         struct task_struct *tsk = current;
+        struct vm_area_struct *vma;
 
         /*
          * If this architecture has a platform capability string, copy it
@@ -234,6 +235,15 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
         sp = (elf_addr_t __user *)bprm->p;
 #endif
 
+
+        /*
+         * Grow the stack manually; some architectures have a limit on how
+         * far ahead a user-space access may be in order to grow the stack.
+         */
+        vma = find_extend_vma(current->mm, bprm->p);
+        if (!vma)
+                return -EFAULT;
+
         /* Now, let's put argc (and argv, envp if appropriate) on the stack */
         if (__put_user(argc, sp++))
                 return -EFAULT;
@@ -254,8 +264,8 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
                 size_t len;
                 if (__put_user((elf_addr_t)p, argv++))
                         return -EFAULT;
-                len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);
-                if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)
+                len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
+                if (!len || len > MAX_ARG_STRLEN)
                         return 0;
                 p += len;
         }
@@ -266,8 +276,8 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
                 size_t len;
                 if (__put_user((elf_addr_t)p, envp++))
                         return -EFAULT;
-                len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);
-                if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)
+                len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
+                if (!len || len > MAX_ARG_STRLEN)
                         return 0;
                 p += len;
         }
@@ -826,10 +836,6 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
         }
 
         /* OK, This is the point of no return */
-        current->mm->start_data = 0;
-        current->mm->end_data = 0;
-        current->mm->end_code = 0;
-        current->mm->mmap = NULL;
         current->flags &= ~PF_FORKNOEXEC;
         current->mm->def_flags = def_flags;
 
@@ -1051,9 +1057,13 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 
         compute_creds(bprm);
         current->flags &= ~PF_FORKNOEXEC;
-        create_elf_tables(bprm, &loc->elf_ex,
+        retval = create_elf_tables(bprm, &loc->elf_ex,
                           (interpreter_type == INTERPRETER_AOUT),
                           load_addr, interp_load_addr);
+        if (retval < 0) {
+                send_sig(SIGKILL, current, 0);
+                goto out;
+        }
         /* N.B. passed_fileno might not be initialized? */
         if (interpreter_type == INTERPRETER_AOUT)
                 current->mm->arg_start += strlen(passed_fileno) + 1;
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 9d62fbad3d4b..4739506fb083 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -621,8 +621,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
         p = (char __user *) current->mm->arg_start;
         for (loop = bprm->argc; loop > 0; loop--) {
                 __put_user((elf_caddr_t) p, argv++);
-                len = strnlen_user(p, PAGE_SIZE * MAX_ARG_PAGES);
-                if (!len || len > PAGE_SIZE * MAX_ARG_PAGES)
+                len = strnlen_user(p, MAX_ARG_STRLEN);
+                if (!len || len > MAX_ARG_STRLEN)
                         return -EINVAL;
                 p += len;
         }
@@ -633,8 +633,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
         current->mm->env_start = (unsigned long) p;
         for (loop = bprm->envc; loop > 0; loop--) {
                 __put_user((elf_caddr_t)(unsigned long) p, envp++);
-                len = strnlen_user(p, PAGE_SIZE * MAX_ARG_PAGES);
-                if (!len || len > PAGE_SIZE * MAX_ARG_PAGES)
+                len = strnlen_user(p, MAX_ARG_STRLEN);
+                if (!len || len > MAX_ARG_STRLEN)
                         return -EINVAL;
                 p += len;
         }
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 330fd3fe8546..42e94b3ab7be 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -126,7 +126,9 @@ static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs)
                 goto _ret;
 
         if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
-                remove_arg_zero(bprm);
+                retval = remove_arg_zero(bprm);
+                if (retval)
+                        goto _ret;
         }
 
         if (fmt->flags & MISC_FMT_OPEN_BINARY) {
diff --git a/fs/binfmt_script.c b/fs/binfmt_script.c
index 304c88544d89..4d0e0f6d3273 100644
--- a/fs/binfmt_script.c
+++ b/fs/binfmt_script.c
@@ -67,7 +67,9 @@ static int load_script(struct linux_binprm *bprm,struct pt_regs *regs)
          * This is done in reverse order, because of how the
          * user environment and arguments are stored.
          */
-        remove_arg_zero(bprm);
+        retval = remove_arg_zero(bprm);
+        if (retval)
+                return retval;
         retval = copy_strings_kernel(1, &bprm->interp, bprm);
         if (retval < 0) return retval; 
         bprm->argc++;
diff --git a/fs/compat.c b/fs/compat.c
index 4db6216e5266..15078ce4c04a 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1257,6 +1257,7 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
 {
         struct page *kmapped_page = NULL;
         char *kaddr = NULL;
+        unsigned long kpos = 0;
         int ret;
 
         while (argc-- > 0) {
@@ -1265,92 +1266,84 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
                 unsigned long pos;
 
                 if (get_user(str, argv+argc) ||
-                        !(len = strnlen_user(compat_ptr(str), bprm->p))) {
+                    !(len = strnlen_user(compat_ptr(str), MAX_ARG_STRLEN))) {
                         ret = -EFAULT;
                         goto out;
                 }
 
-                if (bprm->p < len)  {
+                if (len > MAX_ARG_STRLEN) {
                         ret = -E2BIG;
                         goto out;
                 }
 
-                bprm->p -= len;
-                /* XXX: add architecture specific overflow check here. */
+                /* We're going to work our way backwords. */
                 pos = bprm->p;
+                str += len;
+                bprm->p -= len;
 
                 while (len > 0) {
-                        int i, new, err;
                         int offset, bytes_to_copy;
-                        struct page *page;
 
                         offset = pos % PAGE_SIZE;
-                        i = pos/PAGE_SIZE;
-                        page = bprm->page[i];
-                        new = 0;
-                        if (!page) {
-                                page = alloc_page(GFP_HIGHUSER);
-                                bprm->page[i] = page;
-                                if (!page) {
-                                        ret = -ENOMEM;
+                        if (offset == 0)
+                                offset = PAGE_SIZE;
+
+                        bytes_to_copy = offset;
+                        if (bytes_to_copy > len)
+                                bytes_to_copy = len;
+
+                        offset -= bytes_to_copy;
+                        pos -= bytes_to_copy;
+                        str -= bytes_to_copy;
+                        len -= bytes_to_copy;
+
+                        if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
+                                struct page *page;
+
+#ifdef CONFIG_STACK_GROWSUP
+                                ret = expand_stack_downwards(bprm->vma, pos);
+                                if (ret < 0) {
+                                        /* We've exceed the stack rlimit. */
+                                        ret = -E2BIG;
+                                        goto out;
+                                }
+#endif
+                                ret = get_user_pages(current, bprm->mm, pos,
+                                                     1, 1, 1, &page, NULL);
+                                if (ret <= 0) {
+                                        /* We've exceed the stack rlimit. */
+                                        ret = -E2BIG;
                                         goto out;
                                 }
-                                new = 1;
-                        }
 
-                        if (page != kmapped_page) {
-                                if (kmapped_page)
+                                if (kmapped_page) {
+                                        flush_kernel_dcache_page(kmapped_page);
                                         kunmap(kmapped_page);
+                                        put_page(kmapped_page);
+                                }
                                 kmapped_page = page;
                                 kaddr = kmap(kmapped_page);
+                                kpos = pos & PAGE_MASK;
+                                flush_cache_page(bprm->vma, kpos,
+                                                 page_to_pfn(kmapped_page));
                         }
-                        if (new && offset)
-                                memset(kaddr, 0, offset);
-                        bytes_to_copy = PAGE_SIZE - offset;
-                        if (bytes_to_copy > len) {
-                                bytes_to_copy = len;
-                                if (new)
-                                        memset(kaddr+offset+len, 0,
-                                                PAGE_SIZE-offset-len);
-                        }
-                        err = copy_from_user(kaddr+offset, compat_ptr(str),
-                                                bytes_to_copy);
-                        if (err) {
+                        if (copy_from_user(kaddr+offset, compat_ptr(str),
+                                                bytes_to_copy)) {
                                 ret = -EFAULT;
                                 goto out;
                         }
-
-                        pos += bytes_to_copy;
-                        str += bytes_to_copy;
-                        len -= bytes_to_copy;
                 }
         }
         ret = 0;
 out:
-        if (kmapped_page)
+        if (kmapped_page) {
+                flush_kernel_dcache_page(kmapped_page);
                 kunmap(kmapped_page);
-        return ret;
-}
-
-#ifdef CONFIG_MMU
-
-#define free_arg_pages(bprm) do { } while (0)
-
-#else
-
-static inline void free_arg_pages(struct linux_binprm *bprm)
-{
-        int i;
-
-        for (i = 0; i < MAX_ARG_PAGES; i++) {
-                if (bprm->page[i])
-                        __free_page(bprm->page[i]);
-                bprm->page[i] = NULL;
+                put_page(kmapped_page);
         }
+        return ret;
 }
 
-#endif /* CONFIG_MMU */
-
 /*
  * compat_do_execve() is mostly a copy of do_execve(), with the exception
  * that it processes 32 bit argv and envp pointers.
@@ -1363,7 +1356,6 @@ int compat_do_execve(char * filename,
         struct linux_binprm *bprm;
         struct file *file;
         int retval;
-        int i;
 
         retval = -ENOMEM;
         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
@@ -1377,24 +1369,19 @@ int compat_do_execve(char * filename,
 
         sched_exec();
 
-        bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
         bprm->file = file;
         bprm->filename = filename;
         bprm->interp = filename;
-        bprm->mm = mm_alloc();
-        retval = -ENOMEM;
-        if (!bprm->mm)
-                goto out_file;
 
-        retval = init_new_context(current, bprm->mm);
-        if (retval < 0)
-                goto out_mm;
+        retval = bprm_mm_init(bprm);
+        if (retval)
+                goto out_file;
 
-        bprm->argc = compat_count(argv, bprm->p / sizeof(compat_uptr_t));
+        bprm->argc = compat_count(argv, MAX_ARG_STRINGS);
         if ((retval = bprm->argc) < 0)
                 goto out_mm;
 
-        bprm->envc = compat_count(envp, bprm->p / sizeof(compat_uptr_t));
+        bprm->envc = compat_count(envp, MAX_ARG_STRINGS);
         if ((retval = bprm->envc) < 0)
                 goto out_mm;
 
@@ -1421,8 +1408,6 @@ int compat_do_execve(char * filename,
 
         retval = search_binary_handler(bprm, regs);
         if (retval >= 0) {
-                free_arg_pages(bprm);
-
                 /* execve success */
                 security_bprm_free(bprm);
                 acct_update_integrals(current);
@@ -1431,19 +1416,12 @@ int compat_do_execve(char * filename,
         }
 
 out:
-        /* Something went wrong, return the inode and free the argument pages*/
-        for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
-                struct page * page = bprm->page[i];
-                if (page)
-                        __free_page(page);
-        }
-
         if (bprm->security)
                 security_bprm_free(bprm);
 
 out_mm:
         if (bprm->mm)
-                mmdrop(bprm->mm);
+                mmput(bprm->mm);
 
 out_file:
         if (bprm->file) {
diff --git a/fs/exec.c b/fs/exec.c
index 2e3f7950c185..498f2b3dca20 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -54,6 +54,7 @@
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
+#include <asm/tlb.h>
 
 #ifdef CONFIG_KMOD
 #include <linux/kmod.h>
@@ -178,6 +179,207 @@ exit:
         goto out;
 }
 
+#ifdef CONFIG_MMU
+
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+                int write)
+{
+        struct page *page;
+        int ret;
+
+#ifdef CONFIG_STACK_GROWSUP
+        if (write) {
+                ret = expand_stack_downwards(bprm->vma, pos);
+                if (ret < 0)
+                        return NULL;
+        }
+#endif
+        ret = get_user_pages(current, bprm->mm, pos,
+                        1, write, 1, &page, NULL);
+        if (ret <= 0)
+                return NULL;
+
+        if (write) {
+                struct rlimit *rlim = current->signal->rlim;
+                unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
+
+                /*
+                 * Limit to 1/4-th the stack size for the argv+env strings.
+                 * This ensures that:
+                 *  - the remaining binfmt code will not run out of stack space,
+                 *  - the program will have a reasonable amount of stack left
+                 *    to work from.
+                 */
+                if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
+                        put_page(page);
+                        return NULL;
+                }
+        }
+
+        return page;
+}
+
+static void put_arg_page(struct page *page)
+{
+        put_page(page);
+}
+
+static void free_arg_page(struct linux_binprm *bprm, int i)
+{
+}
+
+static void free_arg_pages(struct linux_binprm *bprm)
+{
+}
+
+static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
+                struct page *page)
+{
+        flush_cache_page(bprm->vma, pos, page_to_pfn(page));
+}
+
+static int __bprm_mm_init(struct linux_binprm *bprm)
+{
+        int err = -ENOMEM;
+        struct vm_area_struct *vma = NULL;
+        struct mm_struct *mm = bprm->mm;
+
+        bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+        if (!vma)
+                goto err;
+
+        down_write(&mm->mmap_sem);
+        vma->vm_mm = mm;
+
+        /*
+         * Place the stack at the largest stack address the architecture
+         * supports. Later, we'll move this to an appropriate place. We don't
+         * use STACK_TOP because that can depend on attributes which aren't
+         * configured yet.
+         */
+        vma->vm_end = STACK_TOP_MAX;
+        vma->vm_start = vma->vm_end - PAGE_SIZE;
+
+        vma->vm_flags = VM_STACK_FLAGS;
+        vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
+        err = insert_vm_struct(mm, vma);
+        if (err) {
+                up_write(&mm->mmap_sem);
+                goto err;
+        }
+
+        mm->stack_vm = mm->total_vm = 1;
+        up_write(&mm->mmap_sem);
+
+        bprm->p = vma->vm_end - sizeof(void *);
+
+        return 0;
+
+err:
+        if (vma) {
+                bprm->vma = NULL;
+                kmem_cache_free(vm_area_cachep, vma);
+        }
+
+        return err;
+}
+
+static bool valid_arg_len(struct linux_binprm *bprm, long len)
+{
+        return len <= MAX_ARG_STRLEN;
+}
+
+#else
+
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+                int write)
+{
+        struct page *page;
+
+        page = bprm->page[pos / PAGE_SIZE];
+        if (!page && write) {
+                page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
+                if (!page)
+                        return NULL;
+                bprm->page[pos / PAGE_SIZE] = page;
+        }
+
+        return page;
+}
+
+static void put_arg_page(struct page *page)
+{
+}
+
+static void free_arg_page(struct linux_binprm *bprm, int i)
+{
+        if (bprm->page[i]) {
+                __free_page(bprm->page[i]);
+                bprm->page[i] = NULL;
+        }
+}
+
+static void free_arg_pages(struct linux_binprm *bprm)
+{
+        int i;
+
+        for (i = 0; i < MAX_ARG_PAGES; i++)
+                free_arg_page(bprm, i);
+}
+
+static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
+                struct page *page)
+{
+}
+
+static int __bprm_mm_init(struct linux_binprm *bprm)
+{
+        bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
+        return 0;
+}
+
+static bool valid_arg_len(struct linux_binprm *bprm, long len)
+{
+        return len <= bprm->p;
+}
+
+#endif /* CONFIG_MMU */
+
+/*
+ * Create a new mm_struct and populate it with a temporary stack
+ * vm_area_struct.  We don't have enough context at this point to set the stack
+ * flags, permissions, and offset, so we use temporary values.  We'll update
+ * them later in setup_arg_pages().
+ */
+int bprm_mm_init(struct linux_binprm *bprm)
+{
+        int err;
+        struct mm_struct *mm = NULL;
+
+        bprm->mm = mm = mm_alloc();
+        err = -ENOMEM;
+        if (!mm)
+                goto err;
+
+        err = init_new_context(current, mm);
+        if (err)
+                goto err;
+
+        err = __bprm_mm_init(bprm);
+        if (err)
+                goto err;
+
+        return 0;
+
+err:
+        if (mm) {
+                bprm->mm = NULL;
+                mmdrop(mm);
+        }
+
+        return err;
+}
+
 /*
  * count() counts the number of strings in array ARGV.
  */
@@ -203,15 +405,16 @@ static int count(char __user * __user * argv, int max)
 }
 
 /*
- * 'copy_strings()' copies argument/environment strings from user
- * memory to free pages in kernel mem. These are in a format ready
- * to be put directly into the top of new user memory.
+ * 'copy_strings()' copies argument/environment strings from the old
+ * processes's memory to the new process's stack.  The call to get_user_pages()
+ * ensures the destination page is created and not swapped out.
  */
 static int copy_strings(int argc, char __user * __user * argv,
                         struct linux_binprm *bprm)
 {
         struct page *kmapped_page = NULL;
         char *kaddr = NULL;
+        unsigned long kpos = 0;
         int ret;
 
         while (argc-- > 0) {
@@ -220,69 +423,69 @@ static int copy_strings(int argc, char __user * __user * argv,
                 unsigned long pos;
 
                 if (get_user(str, argv+argc) ||
-                                !(len = strnlen_user(str, bprm->p))) {
+                                !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
                         ret = -EFAULT;
                         goto out;
                 }
 
-                if (bprm->p < len)  {
+                if (!valid_arg_len(bprm, len)) {
                         ret = -E2BIG;
                         goto out;
                 }
 
-                bprm->p -= len;
-                /* XXX: add architecture specific overflow check here. */
+                /* We're going to work our way backwords. */
                 pos = bprm->p;
+                str += len;
+                bprm->p -= len;
 
                 while (len > 0) {
-                        int i, new, err;
                         int offset, bytes_to_copy;
-                        struct page *page;
 
                         offset = pos % PAGE_SIZE;
-                        i = pos/PAGE_SIZE;
-                        page = bprm->page[i];
-                        new = 0;
-                        if (!page) {
-                                page = alloc_page(GFP_HIGHUSER);
-                                bprm->page[i] = page;
+                        if (offset == 0)
+                                offset = PAGE_SIZE;
+
+                        bytes_to_copy = offset;
+                        if (bytes_to_copy > len)
+                                bytes_to_copy = len;
+
+                        offset -= bytes_to_copy;
+                        pos -= bytes_to_copy;
+                        str -= bytes_to_copy;
+                        len -= bytes_to_copy;
+
+                        if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
+                                struct page *page;
+
+                                page = get_arg_page(bprm, pos, 1);
                                 if (!page) {
-                                        ret = -ENOMEM;
+                                        ret = -E2BIG;
                                         goto out;
                                 }
-                                new = 1;
-                        }
 
-                        if (page != kmapped_page) {
-                                if (kmapped_page)
+                                if (kmapped_page) {
+                                        flush_kernel_dcache_page(kmapped_page);
                                         kunmap(kmapped_page);
+                                        put_arg_page(kmapped_page);
+                                }
                                 kmapped_page = page;
                                 kaddr = kmap(kmapped_page);
+                                kpos = pos & PAGE_MASK;
+                                flush_arg_page(bprm, kpos, kmapped_page);
                         }
-                        if (new && offset)
-                                memset(kaddr, 0, offset);
-                        bytes_to_copy = PAGE_SIZE - offset;
-                        if (bytes_to_copy > len) {
-                                bytes_to_copy = len;
-                                if (new)
-                                        memset(kaddr+offset+len, 0,
-                                                PAGE_SIZE-offset-len);
-                        }
-                        err = copy_from_user(kaddr+offset, str, bytes_to_copy);
-                        if (err) {
+                        if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
                                 ret = -EFAULT;
                                 goto out;
                         }
-
-                        pos += bytes_to_copy;
-                        str += bytes_to_copy;
-                        len -= bytes_to_copy;
                 }
         }
         ret = 0;
 out:
-        if (kmapped_page)
+        if (kmapped_page) {
+                flush_kernel_dcache_page(kmapped_page);
                 kunmap(kmapped_page);
+                put_arg_page(kmapped_page);
+        }
         return ret;
 }
 
@@ -298,181 +501,172 @@ int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
         set_fs(oldfs);
         return r;
 }
-
 EXPORT_SYMBOL(copy_strings_kernel);
 
 #ifdef CONFIG_MMU
+
 /*
- * This routine is used to map in a page into an address space: needed by
- * execve() for the initial stack and environment pages.
+ * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
+ * the binfmt code determines where the new stack should reside, we shift it to
+ * its final location.  The process proceeds as follows:
  *
- * vma->vm_mm->mmap_sem is held for writing.
+ * 1) Use shift to calculate the new vma endpoints.
+ * 2) Extend vma to cover both the old and new ranges.  This ensures the
+ *    arguments passed to subsequent functions are consistent.
+ * 3) Move vma's page tables to the new range.
+ * 4) Free up any cleared pgd range.
+ * 5) Shrink the vma to cover only the new range.
  */
-void install_arg_page(struct vm_area_struct *vma,
-                        struct page *page, unsigned long address)
+static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 {
         struct mm_struct *mm = vma->vm_mm;
-        pte_t * pte;
-        spinlock_t *ptl;
+        unsigned long old_start = vma->vm_start;
+        unsigned long old_end = vma->vm_end;
+        unsigned long length = old_end - old_start;
+        unsigned long new_start = old_start - shift;
+        unsigned long new_end = old_end - shift;
+        struct mmu_gather *tlb;
 
-        if (unlikely(anon_vma_prepare(vma)))
-                goto out;
+        BUG_ON(new_start > new_end);
 
-        flush_dcache_page(page);
-        pte = get_locked_pte(mm, address, &ptl);
-        if (!pte)
-                goto out;
-        if (!pte_none(*pte)) {
-                pte_unmap_unlock(pte, ptl);
-                goto out;
+        /*
+         * ensure there are no vmas between where we want to go
+         * and where we are
+         */
+        if (vma != find_vma(mm, new_start))
+                return -EFAULT;
+
+        /*
+         * cover the whole range: [new_start, old_end)
+         */
+        vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
+
+        /*
+         * move the page tables downwards, on failure we rely on
+         * process cleanup to remove whatever mess we made.
+         */
+        if (length != move_page_tables(vma, old_start,
+                                       vma, new_start, length))
+                return -ENOMEM;
+
+        lru_add_drain();
+        tlb = tlb_gather_mmu(mm, 0);
+        if (new_end > old_start) {
+                /*
+                 * when the old and new regions overlap clear from new_end.
+                 */
+                free_pgd_range(&tlb, new_end, old_end, new_end,
+                        vma->vm_next ? vma->vm_next->vm_start : 0);
+        } else {
+                /*
+                 * otherwise, clean from old_start; this is done to not touch
+                 * the address space in [new_end, old_start) some architectures
+                 * have constraints on va-space that make this illegal (IA64) -
+                 * for the others its just a little faster.
+                 */
+                free_pgd_range(&tlb, old_start, old_end, new_end,
+                        vma->vm_next ? vma->vm_next->vm_start : 0);
         }
-        inc_mm_counter(mm, anon_rss);
-        lru_cache_add_active(page);
-        set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
-                                        page, vma->vm_page_prot))));
-        page_add_new_anon_rmap(page, vma, address);
-        pte_unmap_unlock(pte, ptl);
-
-        /* no need for flush_tlb */
-        return;
-out:
-        __free_page(page);
-        force_sig(SIGKILL, current);
+        tlb_finish_mmu(tlb, new_end, old_end);
+
+        /*
+         * shrink the vma to just the new range.
+         */
+        vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
+
+        return 0;
 }
 
 #define EXTRA_STACK_VM_PAGES    20      /* random */
 
+/*
+ * Finalizes the stack vm_area_struct. The flags and permissions are updated,
+ * the stack is optionally relocated, and some extra space is added.
+ */
 int setup_arg_pages(struct linux_binprm *bprm,
                     unsigned long stack_top,
                     int executable_stack)
 {
-        unsigned long stack_base;
-        struct vm_area_struct *mpnt;
+        unsigned long ret;
+        unsigned long stack_shift;
         struct mm_struct *mm = current->mm;
-        int i, ret;
-        long arg_size;
+        struct vm_area_struct *vma = bprm->vma;
+        struct vm_area_struct *prev = NULL;
+        unsigned long vm_flags;
+        unsigned long stack_base;
 
 #ifdef CONFIG_STACK_GROWSUP
-        /* Move the argument and environment strings to the bottom of the
-         * stack space.
-         */
-        int offset, j;
-        char *to, *from;
-
-        /* Start by shifting all the pages down */
-        i = 0;
-        for (j = 0; j < MAX_ARG_PAGES; j++) {
-                struct page *page = bprm->page[j];
-                if (!page)
-                        continue;
-                bprm->page[i++] = page;
-        }
-
-        /* Now move them within their pages */
-        offset = bprm->p % PAGE_SIZE;
-        to = kmap(bprm->page[0]);
-        for (j = 1; j < i; j++) {
-                memmove(to, to + offset, PAGE_SIZE - offset);
-                from = kmap(bprm->page[j]);
-                memcpy(to + PAGE_SIZE - offset, from, offset);
-                kunmap(bprm->page[j - 1]);
-                to = from;
-        }
-        memmove(to, to + offset, PAGE_SIZE - offset);
-        kunmap(bprm->page[j - 1]);
-
         /* Limit stack size to 1GB */
         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
         if (stack_base > (1 << 30))
                 stack_base = 1 << 30;
-        stack_base = PAGE_ALIGN(stack_top - stack_base);
 
-        /* Adjust bprm->p to point to the end of the strings. */
-        bprm->p = stack_base + PAGE_SIZE * i - offset;
+        /* Make sure we didn't let the argument array grow too large. */
+        if (vma->vm_end - vma->vm_start > stack_base)
+                return -ENOMEM;
 
-        mm->arg_start = stack_base;
-        arg_size = i << PAGE_SHIFT;
+        stack_base = PAGE_ALIGN(stack_top - stack_base);
 
-        /* zero pages that were copied above */
-        while (i < MAX_ARG_PAGES)
-                bprm->page[i++] = NULL;
+        stack_shift = vma->vm_start - stack_base;
+        mm->arg_start = bprm->p - stack_shift;
+        bprm->p = vma->vm_end - stack_shift;
 #else
-        stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
-        stack_base = PAGE_ALIGN(stack_base);
-        bprm->p += stack_base;
+        stack_top = arch_align_stack(stack_top);
+        stack_top = PAGE_ALIGN(stack_top);
+        stack_shift = vma->vm_end - stack_top;
+
+        bprm->p -= stack_shift;
         mm->arg_start = bprm->p;
-        arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
 #endif
 
-        arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
-
         if (bprm->loader)
-                bprm->loader += stack_base;
-        bprm->exec += stack_base;
-
-        mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
-        if (!mpnt)
-                return -ENOMEM;
+                bprm->loader -= stack_shift;
+        bprm->exec -= stack_shift;
 
         down_write(&mm->mmap_sem);
-        {
-                mpnt->vm_mm = mm;
-#ifdef CONFIG_STACK_GROWSUP
-                mpnt->vm_start = stack_base;
-                mpnt->vm_end = stack_base + arg_size;
-#else
-                mpnt->vm_end = stack_top;
-                mpnt->vm_start = mpnt->vm_end - arg_size;
-#endif
-                /* Adjust stack execute permissions; explicitly enable
-                 * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
-                 * and leave alone (arch default) otherwise. */
-                if (unlikely(executable_stack == EXSTACK_ENABLE_X))
-                        mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
-                else if (executable_stack == EXSTACK_DISABLE_X)
-                        mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
-                else
-                        mpnt->vm_flags = VM_STACK_FLAGS;
-                mpnt->vm_flags |= mm->def_flags;
-                mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
-                if ((ret = insert_vm_struct(mm, mpnt))) {
+        vm_flags = vma->vm_flags;
+
+        /*
+         * Adjust stack execute permissions; explicitly enable for
+         * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
+         * (arch default) otherwise.
+         */
+        if (unlikely(executable_stack == EXSTACK_ENABLE_X))
+                vm_flags |= VM_EXEC;
+        else if (executable_stack == EXSTACK_DISABLE_X)
+                vm_flags &= ~VM_EXEC;
+        vm_flags |= mm->def_flags;
+
+        ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
+                        vm_flags);
+        if (ret)
+                goto out_unlock;
+        BUG_ON(prev != vma);
+
+        /* Move stack pages down in memory. */
+        if (stack_shift) {
+                ret = shift_arg_pages(vma, stack_shift);
+                if (ret) {
                         up_write(&mm->mmap_sem);
-                        kmem_cache_free(vm_area_cachep, mpnt);
                         return ret;
                 }
-                mm->stack_vm = mm->total_vm = vma_pages(mpnt);
         }
 
-        for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
-                struct page *page = bprm->page[i];
-                if (page) {
-                        bprm->page[i] = NULL;
-                        install_arg_page(mpnt, page, stack_base);
-                }
-                stack_base += PAGE_SIZE;
-        }
+#ifdef CONFIG_STACK_GROWSUP
+        stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+#else
+        stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+#endif
+        ret = expand_stack(vma, stack_base);
+        if (ret)
+                ret = -EFAULT;
+
+out_unlock:
         up_write(&mm->mmap_sem);
-        
         return 0;
 }
-
 EXPORT_SYMBOL(setup_arg_pages);
 
-#define free_arg_pages(bprm) do { } while (0)
-
-#else
-
-static inline void free_arg_pages(struct linux_binprm *bprm)
-{
-        int i;
-
-        for (i = 0; i < MAX_ARG_PAGES; i++) {
-                if (bprm->page[i])
-                        __free_page(bprm->page[i]);
-                bprm->page[i] = NULL;
-        }
-}
-
 #endif /* CONFIG_MMU */
 
 struct file *open_exec(const char *name)
@@ -1000,43 +1194,42 @@ EXPORT_SYMBOL(compute_creds);
  * points to; chop off the first by relocating brpm->p to right after
  * the first '\0' encountered.
  */
-void remove_arg_zero(struct linux_binprm *bprm)
+int remove_arg_zero(struct linux_binprm *bprm)
 {
-        if (bprm->argc) {
-                char ch;
+        int ret = 0;
+        unsigned long offset;
+        char *kaddr;
+        struct page *page;
 
-                do {
-                        unsigned long offset;
-                        unsigned long index;
-                        char *kaddr;
-                        struct page *page;
-
-                        offset = bprm->p & ~PAGE_MASK;
-                        index = bprm->p >> PAGE_SHIFT;
+        if (!bprm->argc)
+                return 0;
 
-                        page = bprm->page[index];
-                        kaddr = kmap_atomic(page, KM_USER0);
+        do {
+                offset = bprm->p & ~PAGE_MASK;
+                page = get_arg_page(bprm, bprm->p, 0);
+                if (!page) {
+                        ret = -EFAULT;
+                        goto out;
+                }
+                kaddr = kmap_atomic(page, KM_USER0);
 
-                        /* run through page until we reach end or find NUL */
-                        do {
-                                ch = *(kaddr + offset);
+                for (; offset < PAGE_SIZE && kaddr[offset];
+                                offset++, bprm->p++)
+                        ;
 
-                                /* discard that character... */
-                                bprm->p++;
-                                offset++;
-                        } while (offset < PAGE_SIZE && ch != '\0');
+                kunmap_atomic(kaddr, KM_USER0);
+                put_arg_page(page);
 
-                        kunmap_atomic(kaddr, KM_USER0);
+                if (offset == PAGE_SIZE)
+                        free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
+        } while (offset == PAGE_SIZE);
 
-                        /* free the old page */
-                        if (offset == PAGE_SIZE) {
-                                __free_page(page);
-                                bprm->page[index] = NULL;
-                        }
-                } while (ch != '\0');
+        bprm->p++;
+        bprm->argc--;
+        ret = 0;
 
-                bprm->argc--;
-        }
+out:
+        return ret;
 }
 EXPORT_SYMBOL(remove_arg_zero);
 
@@ -1062,7 +1255,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
                 fput(bprm->file);
                 bprm->file = NULL;
 
-                loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
+                loader = bprm->vma->vm_end - sizeof(void *);
 
                 file = open_exec("/sbin/loader");
                 retval = PTR_ERR(file);
@@ -1156,7 +1349,6 @@ int do_execve(char * filename,
         struct file *file;
         unsigned long env_p;
         int retval;
-        int i;
 
         retval = -ENOMEM;
         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
@@ -1170,25 +1362,19 @@ int do_execve(char * filename,
 
         sched_exec();
 
-        bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
-
         bprm->file = file;
         bprm->filename = filename;
         bprm->interp = filename;
-        bprm->mm = mm_alloc();
-        retval = -ENOMEM;
-        if (!bprm->mm)
-                goto out_file;
 
-        retval = init_new_context(current, bprm->mm);
-        if (retval < 0)
-                goto out_mm;
+        retval = bprm_mm_init(bprm);
+        if (retval)
+                goto out_file;
 
-        bprm->argc = count(argv, bprm->p / sizeof(void *));
+        bprm->argc = count(argv, MAX_ARG_STRINGS);
         if ((retval = bprm->argc) < 0)
                 goto out_mm;
 
-        bprm->envc = count(envp, bprm->p / sizeof(void *));
+        bprm->envc = count(envp, MAX_ARG_STRINGS);
         if ((retval = bprm->envc) < 0)
                 goto out_mm;
 
@@ -1217,9 +1403,8 @@ int do_execve(char * filename,
 
         retval = search_binary_handler(bprm,regs);
         if (retval >= 0) {
-                free_arg_pages(bprm);
-
                 /* execve success */
+                free_arg_pages(bprm);
                 security_bprm_free(bprm);
                 acct_update_integrals(current);
                 kfree(bprm);
@@ -1227,26 +1412,19 @@ int do_execve(char * filename,
         }
 
 out:
-        /* Something went wrong, return the inode and free the argument pages*/
-        for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
-                struct page * page = bprm->page[i];
-                if (page)
-                        __free_page(page);
-        }
-
+        free_arg_pages(bprm);
         if (bprm->security)
                 security_bprm_free(bprm);
 
 out_mm:
         if (bprm->mm)
-                mmdrop(bprm->mm);
+                mmput (bprm->mm);
 
 out_file:
         if (bprm->file) {
                 allow_write_access(bprm->file);
                 fput(bprm->file);
         }
-
 out_kfree:
         kfree(bprm);