1 files changed, 100 insertions, 25 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 8328beb9016f..c016896dcbb2 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -55,6 +55,7 @@
 #include <linux/fs_struct.h>
 #include <linux/pipe_fs_i.h>
 #include <linux/oom.h>
+#include <linux/compat.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -166,8 +167,13 @@ out:
 }
 
 #ifdef CONFIG_MMU
-
-void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
+/*
+ * The nascent bprm->mm is not visible until exec_mmap() but it can
+ * use a lot of memory, account these pages in current->mm temporary
+ * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
+ * change the counter back via acct_arg_size(0).
+ */
+static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 {
         struct mm_struct *mm = current->mm;
         long diff = (long)(pages - bprm->vma_pages);
@@ -186,7 +192,7 @@ void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 #endif
 }
 
-struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
                 int write)
 {
         struct page *page;
@@ -305,11 +311,11 @@ static bool valid_arg_len(struct linux_binprm *bprm, long len)
 
 #else
 
-void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
+static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 {
 }
 
-struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
                 int write)
 {
         struct page *page;
@@ -398,22 +404,56 @@ err:
         return err;
 }
 
+struct user_arg_ptr {
+#ifdef CONFIG_COMPAT
+        bool is_compat;
+#endif
+        union {
+                const char __user *const __user *native;
+#ifdef CONFIG_COMPAT
+                compat_uptr_t __user *compat;
+#endif
+        } ptr;
+};
+
+static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
+{
+        const char __user *native;
+
+#ifdef CONFIG_COMPAT
+        if (unlikely(argv.is_compat)) {
+                compat_uptr_t compat;
+
+                if (get_user(compat, argv.ptr.compat + nr))
+                        return ERR_PTR(-EFAULT);
+
+                return compat_ptr(compat);
+        }
+#endif
+
+        if (get_user(native, argv.ptr.native + nr))
+                return ERR_PTR(-EFAULT);
+
+        return native;
+}
+
 /*
  * count() counts the number of strings in array ARGV.
  */
-static int count(const char __user * const __user * argv, int max)
+static int count(struct user_arg_ptr argv, int max)
 {
         int i = 0;
 
-        if (argv != NULL) {
+        if (argv.ptr.native != NULL) {
                 for (;;) {
-                        const char __user * p;
+                        const char __user *p = get_user_arg_ptr(argv, i);
 
-                        if (get_user(p, argv))
-                                return -EFAULT;
                         if (!p)
                                 break;
-                        argv++;
+
+                        if (IS_ERR(p))
+                                return -EFAULT;
+
                         if (i++ >= max)
                                 return -E2BIG;
 
@@ -430,7 +470,7 @@ static int count(const char __user * const __user * argv, int max)
  * 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, const char __user *const __user *argv,
+static int copy_strings(int argc, struct user_arg_ptr argv,
                         struct linux_binprm *bprm)
 {
         struct page *kmapped_page = NULL;
@@ -443,16 +483,18 @@ static int copy_strings(int argc, const char __user *const __user *argv,
                 int len;
                 unsigned long pos;
 
-                if (get_user(str, argv+argc) ||
-                                !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
-                        ret = -EFAULT;
+                ret = -EFAULT;
+                str = get_user_arg_ptr(argv, argc);
+                if (IS_ERR(str))
                         goto out;
-                }
 
-                if (!valid_arg_len(bprm, len)) {
-                        ret = -E2BIG;
+                len = strnlen_user(str, MAX_ARG_STRLEN);
+                if (!len)
+                        goto out;
+
+                ret = -E2BIG;
+                if (!valid_arg_len(bprm, len))
                         goto out;
-                }
 
                 /* We're going to work our way backwords. */
                 pos = bprm->p;
@@ -519,14 +561,19 @@ out:
 /*
  * Like copy_strings, but get argv and its values from kernel memory.
  */
-int copy_strings_kernel(int argc, const char *const *argv,
+int copy_strings_kernel(int argc, const char *const *__argv,
                         struct linux_binprm *bprm)
 {
         int r;
         mm_segment_t oldfs = get_fs();
+        struct user_arg_ptr argv = {
+                .ptr.native = (const char __user *const  __user *)__argv,
+        };
+
         set_fs(KERNEL_DS);
-        r = copy_strings(argc, (const char __user *const  __user *)argv, bprm);
+        r = copy_strings(argc, argv, bprm);
         set_fs(oldfs);
+
         return r;
 }
 EXPORT_SYMBOL(copy_strings_kernel);
@@ -1379,10 +1426,10 @@ EXPORT_SYMBOL(search_binary_handler);
 /*
  * sys_execve() executes a new program.
  */
-int do_execve(const char * filename,
-        const char __user *const __user *argv,
-        const char __user *const __user *envp,
-        struct pt_regs * regs)
+static int do_execve_common(const char *filename,
+                                struct user_arg_ptr argv,
+                                struct user_arg_ptr envp,
+                                struct pt_regs *regs)
 {
         struct linux_binprm *bprm;
         struct file *file;
@@ -1489,6 +1536,34 @@ out_ret:
         return retval;
 }
 
+int do_execve(const char *filename,
+        const char __user *const __user *__argv,
+        const char __user *const __user *__envp,
+        struct pt_regs *regs)
+{
+        struct user_arg_ptr argv = { .ptr.native = __argv };
+        struct user_arg_ptr envp = { .ptr.native = __envp };
+        return do_execve_common(filename, argv, envp, regs);
+}
+
+#ifdef CONFIG_COMPAT
+int compat_do_execve(char *filename,
+        compat_uptr_t __user *__argv,
+        compat_uptr_t __user *__envp,
+        struct pt_regs *regs)
+{
+        struct user_arg_ptr argv = {
+                .is_compat = true,
+                .ptr.compat = __argv,
+        };
+        struct user_arg_ptr envp = {
+                .is_compat = true,
+                .ptr.compat = __envp,
+        };
+        return do_execve_common(filename, argv, envp, regs);
+}
+#endif
+
 void set_binfmt(struct linux_binfmt *new)
 {
         struct mm_struct *mm = current->mm;