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authorStanislav Kinsbursky <skinsbursky@parallels.com>2012-11-26 16:29:42 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-11-26 17:41:24 -0800
commit05f564849d49499ced97913a0914b5950577d07d (patch)
treeeaab16738a3d405084466d5a9aca01db37e41f73 /fs/proc
parent56c176c9cac9a77249fa1736bfd792f379d61942 (diff)
proc: check vma->vm_file before dereferencing
Commit 7b540d0646ce ("proc_map_files_readdir(): don't bother with grabbing files") switched proc_map_files_readdir() to use @f_mode directly instead of grabbing @file reference, but same time the test for @vm_file presence was lost leading to nil dereference. The patch brings the test back. The all proc_map_files feature is CONFIG_CHECKPOINT_RESTORE wrapped (which is set to 'n' by default) so the bug doesn't affect regular kernels. The regression is 3.7-rc1 only as far as I can tell. [gorcunov@openvz.org: provided changelog] Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 3c231adf8450..9e28356a959a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1877,8 +1877,9 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
if (!vma)
goto out_no_vma;
- result = proc_map_files_instantiate(dir, dentry, task,
- (void *)(unsigned long)vma->vm_file->f_mode);
+ if (vma->vm_file)
+ result = proc_map_files_instantiate(dir, dentry, task,
+ (void *)(unsigned long)vma->vm_file->f_mode);
out_no_vma:
up_read(&mm->mmap_sem);