linux-kernel - [PATCH] jfs: check if dmt

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Message-ID: <tencent_8FB36BE36BC97A03AE44421765577706C905@qq.com>
Date: Fri, 26 Jul 2024 22:22:19 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+dca05492eff41f604890@...kaller.appspotmail.com
Cc: jfs-discussion@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	shaggy@...nel.org,
	syzkaller-bugs@...glegroups.com
Subject: [PATCH] jfs: check if dmt_leafidx is less than zero

syzbot report a out of bounds in dbSplit, it because dmt_leafidx less
than 0, add a checking for dmt_leafidx in dbAllocDmapLev.

Reported-by: syzbot+dca05492eff41f604890@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=dca05492eff41f604890
Signed-off-by: Edward Adam Davis <eadavis@...com>
---
 fs/jfs/jfs_dmap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index cb3cda1390ad..c5b8883599e3 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -1956,6 +1956,7 @@ dbAllocDmapLev(struct bmap * bmp,
 {
 	s64 blkno;
 	int leafidx, rc;
+	dmtree_t *tp = (dmtree_t *) &dp->tree;
 
 	/* can't be more than a dmaps worth of blocks */
 	assert(l2nb <= L2BPERDMAP);
@@ -1964,10 +1965,10 @@ dbAllocDmapLev(struct bmap * bmp,
 	 * free space.  if sufficient free space is found, dbFindLeaf()
 	 * returns the index of the leaf at which free space was found.
 	 */
-	if (dbFindLeaf((dmtree_t *) &dp->tree, l2nb, &leafidx, false))
+	if (dbFindLeaf(tp, l2nb, &leafidx, false))
 		return -ENOSPC;
 
-	if (leafidx < 0)
+	if (leafidx < 0 || le32_to_cpu(tp->dmt_leafidx) < 0)
 		return -EIO;
 
 	/* determine the block number within the file system corresponding
-- 
2.43.0