commit: 1a4022f88d40e1255920b017556092ab926d7f66
From: Erez Zadok <[email protected]>
Date: Sat, 21 May 2011 01:19:59 -0400
Subject: [PATCH] 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 <[email protected]>
Acked-by: Miklos Szeredi <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
---
 fs/namei.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index e3c4f11..6ff858c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1378,12 +1378,12 @@ 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++;

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