From: Pei Li peili.dev@gmail.com

stable inclusion from stable-v6.6.47 commit f650148b43949ca9e37e820804bb6026fff404f3 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAMMML CVE: CVE-2024-44938

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 7063b80268e2593e58bee8a8d709c2f3ff93e2f2 ]

When searching for the next smaller log2 block, BLKSTOL2() returned 0, causing shift exponent -1 to be negative.

This patch fixes the issue by exiting the loop directly when negative shift is found.

Reported-by: syzbot+61be3359d2ee3467e7e4@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=61be3359d2ee3467e7e4 Signed-off-by: Pei Li peili.dev@gmail.com Signed-off-by: Dave Kleikamp dave.kleikamp@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: GONG Ruiqi gongruiqi1@huawei.com --- fs/jfs/jfs_dmap.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index cb3cda1390ad..5713994328cb 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -1626,6 +1626,8 @@ s64 dbDiscardAG(struct inode *ip, int agno, s64 minlen) } else if (rc == -ENOSPC) { /* search for next smaller log2 block */ l2nb = BLKSTOL2(nblocks) - 1; + if (unlikely(l2nb < 0)) + break; nblocks = 1LL << l2nb; } else { /* Trim any already allocated blocks */