From 0225e10972fa809728b8d4c1bd2772b3ec3fdb57 Mon Sep 17 00:00:00 2001
From: Alexei Filippov <halip0503@gmail.com>
Date: Sat, 19 Aug 2023 20:32:16 +0300
Subject: [PATCH] jfs: validate max amount of blocks before allocation.
Git-commit: 0225e10972fa809728b8d4c1bd2772b3ec3fdb57
Patch-mainline: v6.6-rc1
References: git-fixes
The lack of checking bmp->db_max_freebud in extBalloc() can lead to
shift out of bounds, so this patch prevents undefined behavior, because
bmp->db_max_freebud == -1 only if there is no free space.
Signed-off-by: Aleksei Filippov <halip0503@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-and-tested-by: syzbot+5f088f29593e6b4c8db8@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?id=01abadbd6ae6a08b1f1987aa61554c6b3ac19ff2
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
fs/jfs/jfs_extent.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/jfs/jfs_extent.c b/fs/jfs/jfs_extent.c
index adaa9ad50d4c..63d21822d309 100644
--- a/fs/jfs/jfs_extent.c
+++ b/fs/jfs/jfs_extent.c
@@ -311,6 +311,11 @@ extBalloc(struct inode *ip, s64 hint, s64 * nblocks, s64 * blkno)
* blocks in the map. in that case, we'll start off with the
* maximum free.
*/
+
+ /* give up if no space left */
+ if (bmp->db_maxfreebud == -1)
+ return -ENOSPC;
+
max = (s64) 1 << bmp->db_maxfreebud;
if (*nblocks >= max && *nblocks > nbperpage)
nb = nblks = (max > nbperpage) ? max : nbperpage;
--
2.43.0