Commit 05f56484 authored Nov 26, 2012 by Stanislav Kinsbursky Committed by Linus Torvalds Nov 26, 2012

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: 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>

parent 56c176c9

fs/proc/base.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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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