Commit fad376fc authored by Liu Shixin via Jfs-discussion's avatar Liu Shixin via Jfs-discussion Committed by Dave Kleikamp
Browse files

fs/jfs: fix shift exponent db_agl2size negative 



As a shift exponent, db_agl2size can not be less than 0. Add the missing
check to fix the shift-out-of-bounds bug reported by syzkaller:

 UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2227:15
 shift exponent -744642816 is negative

Reported-by: default avatar <syzbot+0be96567042453c0c820@syzkaller.appspotmail.com>
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
Signed-off-by: default avatarDave Kleikamp <dave.kleikamp@oracle.com>
parent 69b41ac8

fs/jfs/jfs_dmap.c

+2 −1
Original line number Diff line number Diff line
@@ -193,7 +193,8 @@ int dbMount(struct inode *ipbmap) 
	bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);

	bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);

	bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);

	if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG) {

	if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG ||

	    bmp->db_agl2size < 0) {

		err = -EINVAL;

		goto err_release_metapage;

	}