From d1de2a81a8c33733fc07320aa5ce2ca2f8698ca8 Mon Sep 17 00:00:00 2001 From: Juntong Deng Date: Mon, 2 Oct 2023 17:56:58 +0800 Subject: [PATCH] fs/jfs: Add check for negative db_l2nbperpage [ Upstream commit 525b861a008143048535011f3816d407940f4bfa ] l2nbperpage is log2(number of blks per page), and the minimum legal value should be 0, not negative. In the case of l2nbperpage being negative, an error will occur when subsequently used as shift exponent. Syzbot reported this bug: UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:799:12 shift exponent -16777216 is negative Reported-by: syzbot+debee9ab7ae2b34b0307@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=debee9ab7ae2b34b0307 Signed-off-by: Juntong Deng Signed-off-by: Dave Kleikamp Signed-off-by: Sasha Levin --- fs/jfs/jfs_dmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index a9c078fc2..06dda2c7a 100755 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -180,7 +180,8 @@ int dbMount(struct inode *ipbmap) bmp->db_nfree = le64_to_cpu(dbmp_le->dn_nfree); bmp->db_l2nbperpage = le32_to_cpu(dbmp_le->dn_l2nbperpage); - if (bmp->db_l2nbperpage > L2PSIZE - L2MINBLOCKSIZE) { + if (bmp->db_l2nbperpage > L2PSIZE - L2MINBLOCKSIZE || + bmp->db_l2nbperpage < 0) { err = -EINVAL; goto err_release_metapage; }