From: Jan Kara <jack@suse.cz>
Date: Tue, 4 Mar 2008 22:28:33 +0000 (-0800)
Subject: vfs: fix NULL pointer dereference in fsync_buffers_list()
X-Git-Tag: v2.6.25-rc4~77
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3892296de632e3f9299d9fabe0c746740004891;p=linux-2.6

vfs: fix NULL pointer dereference in fsync_buffers_list()

Fix NULL pointer dereference in fsync_buffers_list() introduced by recent fix
of races in private_list handling.  Since bh->b_assoc_map has been cleared in
__remove_assoc_queue() we should really use original value stored in the
'mapping' variable.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/buffer.c b/fs/buffer.c
index 897cd7477b..ddfdd2c80b 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -835,7 +835,7 @@ static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
 		smp_mb();
 		if (buffer_dirty(bh)) {
 			list_add(&bh->b_assoc_buffers,
-				 &bh->b_assoc_map->private_list);
+				 &mapping->private_list);
 			bh->b_assoc_map = mapping;
 		}
 		spin_unlock(lock);