On Mon, 2006-12-18 at 19:51 +0100, Eric Sesterhenn wrote:
> hi,
>
> while playing around with fsfuzzer, i got the following oops with jfs:
>
> [ 851.804875] BUG at fs/jfs/jfs_xtree.c:760 assert(!BT_STACK_FULL(btstack))
> [ 851.805179] ------------[ cut here ]------------
> [ 851.805238] kernel BUG at fs/jfs/jfs_xtree.c:760!
...
> On a damaged filesystem we might have a full stack and should
> not progress further, and return instead of calling BUG()
>
> Signed-off-by: Eric Sesterhenn
>
> --- linux-2.6.19/fs/jfs/jfs_xtree.c.orig 2006-12-18 14:37:07.000000000 +0100
> +++ linux-2.6.19/fs/jfs/jfs_xtree.c 2006-12-18 14:37:55.000000000 +0100
> @@ -757,6 +757,8 @@ static int xtSearch(struct inode *ip, s6
> nsplit = 0;
>
> /* push (bn, index) of the parent page/entry */
> + if (BT_STACK_FULL(btstack))
> + return -EINVAL;
This leaks a reference on an xtree page. I'd also like to mark the
superblock dirty here, so that fsck.jfs will fix the file system on the
next boot. jfs_error does this as well as the requested error action.
The default is to remount read-only.
> BT_PUSH(btstack, bn, index);
>
> /* get the child page block number */
>
Do you want to retry your fsfuzzer testing with this patch? I'm going
to take a look at the other calls to BT_PUSH in xtTruncate and
xtTruncate_pmap, but I'm too busy now, so I'll send you what I have so
far (untested).
Signed-off-by: Dave Kleikamp <[email protected]>
diff --git a/fs/jfs/jfs_xtree.c b/fs/jfs/jfs_xtree.c
index e98eb03..176e984 100644
--- a/fs/jfs/jfs_xtree.c
+++ b/fs/jfs/jfs_xtree.c
@@ -757,6 +757,11 @@ static int xtSearch(struct inode *ip, s64 xoff, s64 *nextp,
nsplit = 0;
/* push (bn, index) of the parent page/entry */
+ if (BT_STACK_FULL(btstack)) {
+ jfs_error(ip->i_sb, "stack overrun in xtSearch!");
+ XT_PUTPAGE(mp);
+ return -EIO;
+ }
BT_PUSH(btstack, bn, index);
/* get the child page block number */
--
David Kleikamp
IBM Linux Technology Center
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