* [PATCH] 2.6.39/40 kernel BUG at fs/namei.c:1381
@ 2011-05-21 5:19 Erez Zadok
2011-05-21 22:27 ` Al Viro
0 siblings, 1 reply; 2+ messages in thread
From: Erez Zadok @ 2011-05-21 5:19 UTC (permalink / raw)
To: Linus Torvalds, akpm, Al Viro, Christoph Hellwig; +Cc: linux-fsdevel, stable
VFS: move BUG_ON test for symlink nd->depth after current->link_count test
This solves a serious VFS-level bug in nested_symlink (which was rewritten from
do_follow_link), and follows the order of depth tests that existed before.
The bug triggers a BUG_ON in fs/namei.c:1381, when running racer with
symlink and rename ops.
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
diff --git a/fs/namei.c b/fs/namei.c
index 017c3fa..7a93387 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1343,12 +1343,12 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
{
int res;
- BUG_ON(nd->depth >= MAX_NESTED_LINKS);
if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
path_put_conditional(path, nd);
path_put(&nd->path);
return -ELOOP;
}
+ BUG_ON(nd->depth >= MAX_NESTED_LINKS);
nd->depth++;
current->link_count++;
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] 2.6.39/40 kernel BUG at fs/namei.c:1381
2011-05-21 5:19 [PATCH] 2.6.39/40 kernel BUG at fs/namei.c:1381 Erez Zadok
@ 2011-05-21 22:27 ` Al Viro
0 siblings, 0 replies; 2+ messages in thread
From: Al Viro @ 2011-05-21 22:27 UTC (permalink / raw)
To: Erez Zadok; +Cc: Linus Torvalds, akpm, Christoph Hellwig, linux-fsdevel, stable
On Sat, May 21, 2011 at 01:19:59AM -0400, Erez Zadok wrote:
> VFS: move BUG_ON test for symlink nd->depth after current->link_count test
>
> This solves a serious VFS-level bug in nested_symlink (which was rewritten from
> do_follow_link), and follows the order of depth tests that existed before.
> The bug triggers a BUG_ON in fs/namei.c:1381, when running racer with
> symlink and rename ops.
Racer has nothing to do with that; just a deeply nested symlink in the middle
of pathname will do.
> - BUG_ON(nd->depth >= MAX_NESTED_LINKS);
> if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
> path_put_conditional(path, nd);
> path_put(&nd->path);
> return -ELOOP;
> }
> + BUG_ON(nd->depth >= MAX_NESTED_LINKS);
ACK (and AFAICS Linus has already applied that).
^ permalink raw reply [flat|nested] 2+ messages in thread
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2011-05-21 5:19 [PATCH] 2.6.39/40 kernel BUG at fs/namei.c:1381 Erez Zadok
2011-05-21 22:27 ` Al Viro
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