4 files changed, 66 insertions, 68 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 7c1e65d54872..442d94fe255c 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1280,9 +1280,6 @@ static int writenote(struct memelfnote *men, struct file *file,
 #define DUMP_WRITE(addr, nr)    \
         if ((size += (nr)) > limit || !dump_write(file, (addr), (nr))) \
                 goto end_coredump;
-#define DUMP_SEEK(off)  \
-        if (!dump_seek(file, (off))) \
-                goto end_coredump;
 
 static void fill_elf_header(struct elfhdr *elf, int segs,
                             u16 machine, u32 flags, u8 osabi)
@@ -2016,7 +2013,8 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un
                 goto end_coredump;
 
         /* Align to page */
-        DUMP_SEEK(dataoff - foffset);
+        if (!dump_seek(file, dataoff - foffset))
+                goto end_coredump;
 
         for (vma = first_vma(current, gate_vma); vma != NULL;
                         vma = next_vma(vma, gate_vma)) {
@@ -2027,33 +2025,19 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un
 
                 for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) {
                         struct page *page;
-                        struct vm_area_struct *tmp_vma;
-
-                        if (get_user_pages(current, current->mm, addr, 1, 0, 1,
-                                                &page, &tmp_vma) <= 0) {
-                                DUMP_SEEK(PAGE_SIZE);
-                        } else {
-                                if (page == ZERO_PAGE(0)) {
-                                        if (!dump_seek(file, PAGE_SIZE)) {
-                                                page_cache_release(page);
-                                                goto end_coredump;
-                                        }
-                                } else {
-                                        void *kaddr;
-                                        flush_cache_page(tmp_vma, addr,
-                                                         page_to_pfn(page));
-                                        kaddr = kmap(page);
-                                        if ((size += PAGE_SIZE) > limit ||
-                                            !dump_write(file, kaddr,
-                                            PAGE_SIZE)) {
-                                                kunmap(page);
-                                                page_cache_release(page);
-                                                goto end_coredump;
-                                        }
-                                        kunmap(page);
-                                }
+                        int stop;
+
+                        page = get_dump_page(addr);
+                        if (page) {
+                                void *kaddr = kmap(page);
+                                stop = ((size += PAGE_SIZE) > limit) ||
+                                        !dump_write(file, kaddr, PAGE_SIZE);
+                                kunmap(page);
                                 page_cache_release(page);
-                        }
+                        } else
+                                stop = !dump_seek(file, PAGE_SIZE);
+                        if (stop)
+                                goto end_coredump;
                 }
         }
 
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 20fbeced472b..76285471073e 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1325,9 +1325,6 @@ static int writenote(struct memelfnote *men, struct file *file)
 #define DUMP_WRITE(addr, nr)    \
         if ((size += (nr)) > limit || !dump_write(file, (addr), (nr))) \
                 goto end_coredump;
-#define DUMP_SEEK(off)  \
-        if (!dump_seek(file, (off))) \
-                goto end_coredump;
 
 static inline void fill_elf_fdpic_header(struct elfhdr *elf, int segs)
 {
@@ -1518,6 +1515,7 @@ static int elf_fdpic_dump_segments(struct file *file, size_t *size,
                            unsigned long *limit, unsigned long mm_flags)
 {
         struct vm_area_struct *vma;
+        int err = 0;
 
         for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
                 unsigned long addr;
@@ -1525,43 +1523,26 @@ static int elf_fdpic_dump_segments(struct file *file, size_t *size,
                 if (!maydump(vma, mm_flags))
                         continue;
 
-                for (addr = vma->vm_start;
-                     addr < vma->vm_end;
-                     addr += PAGE_SIZE
-                     ) {
-                        struct vm_area_struct *vma;
-                        struct page *page;
-
-                        if (get_user_pages(current, current->mm, addr, 1, 0, 1,
-                                           &page, &vma) <= 0) {
-                                DUMP_SEEK(file->f_pos + PAGE_SIZE);
-                        }
-                        else if (page == ZERO_PAGE(0)) {
-                                page_cache_release(page);
-                                DUMP_SEEK(file->f_pos + PAGE_SIZE);
-                        }
-                        else {
-                                void *kaddr;
-
-                                flush_cache_page(vma, addr, page_to_pfn(page));
-                                kaddr = kmap(page);
-                                if ((*size += PAGE_SIZE) > *limit ||
-                                    !dump_write(file, kaddr, PAGE_SIZE)
-                                    ) {
-                                        kunmap(page);
-                                        page_cache_release(page);
-                                        return -EIO;
-                                }
+                for (addr = vma->vm_start; addr < vma->vm_end;
+                                                        addr += PAGE_SIZE) {
+                        struct page *page = get_dump_page(addr);
+                        if (page) {
+                                void *kaddr = kmap(page);
+                                *size += PAGE_SIZE;
+                                if (*size > *limit)
+                                        err = -EFBIG;
+                                else if (!dump_write(file, kaddr, PAGE_SIZE))
+                                        err = -EIO;
                                 kunmap(page);
                                 page_cache_release(page);
-                        }
+                        } else if (!dump_seek(file, file->f_pos + PAGE_SIZE))
+                                err = -EFBIG;
+                        if (err)
+                                goto out;
                 }
         }
-
-        return 0;
-
-end_coredump:
-        return -EFBIG;
+out:
+        return err;
 }
 #endif
 
@@ -1802,7 +1783,8 @@ static int elf_fdpic_core_dump(long signr, struct pt_regs *regs,
                                 goto end_coredump;
         }
 
-        DUMP_SEEK(dataoff);
+        if (!dump_seek(file, dataoff))
+                goto end_coredump;
 
         if (elf_fdpic_dump_segments(file, &size, &limit, mm_flags) < 0)
                 goto end_coredump;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 19ff81c49ba6..e41795bba95d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -817,6 +817,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                         struct page **pages, struct vm_area_struct **vmas);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
                         struct page **pages);
+struct page *get_dump_page(unsigned long addr);
 
 extern int try_to_release_page(struct page * page, gfp_t gfp_mask);
 extern void do_invalidatepage(struct page *page, unsigned long offset);
diff --git a/mm/memory.c b/mm/memory.c
index 4b5200f5f35a..a8430ff13837 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1423,9 +1423,40 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 
         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
 }
-
 EXPORT_SYMBOL(get_user_pages);
 
+/**
+ * get_dump_page() - pin user page in memory while writing it to core dump
+ * @addr: user address
+ *
+ * Returns struct page pointer of user page pinned for dump,
+ * to be freed afterwards by page_cache_release() or put_page().
+ *
+ * Returns NULL on any kind of failure - a hole must then be inserted into
+ * the corefile, to preserve alignment with its headers; and also returns
+ * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
+ * allowing a hole to be left in the corefile to save diskspace.
+ *
+ * Called without mmap_sem, but after all other threads have been killed.
+ */
+#ifdef CONFIG_ELF_CORE
+struct page *get_dump_page(unsigned long addr)
+{
+        struct vm_area_struct *vma;
+        struct page *page;
+
+        if (__get_user_pages(current, current->mm, addr, 1,
+                                GUP_FLAGS_FORCE, &page, &vma) < 1)
+                return NULL;
+        if (page == ZERO_PAGE(0)) {
+                page_cache_release(page);
+                return NULL;
+        }
+        flush_cache_page(vma, addr, page_to_pfn(page));
+        return page;
+}
+#endif /* CONFIG_ELF_CORE */
+
 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
                         spinlock_t **ptl)
 {