From: Pei Li <peili.dev@xxxxxxxxx> [ 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@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=61be3359d2ee3467e7e4 Signed-off-by: Pei Li <peili.dev@xxxxxxxxx> Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 deb54efb56013..b89d060af7405 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -1694,6 +1694,8 @@ 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 */ -- 2.43.0
