Commit 05f56484 authored by Stanislav Kinsbursky's avatar Stanislav Kinsbursky Committed by Linus Torvalds

proc: check vma->vm_file before dereferencing

Commit 7b540d06 ("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: default avatarStanislav Kinsbursky <skinsbursky@parallels.com>
Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 56c176c9
......@@ -1877,6 +1877,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
if (!vma)
goto out_no_vma;
if (vma->vm_file)
result = proc_map_files_instantiate(dir, dentry, task,
(void *)(unsigned long)vma->vm_file->f_mode);
......
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