From: Hoi Pok Wu <wuhoipok@gmail.com>
Date: Tue, 25 Oct 2022 15:20:45 +0000 (+0800)
Subject: fs: jfs: fix shift-out-of-bounds in dbDiscardAG
X-Git-Tag: v4.9.337~70
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f8d4d0bac603616e2fa4a3907e81ed13f8f3c380;p=thirdparty%2Fkernel%2Fstable.git

fs: jfs: fix shift-out-of-bounds in dbDiscardAG

[ Upstream commit 25e70c6162f207828dd405b432d8f2a98dbf7082 ]

This should be applied to most URSAN bugs found recently by syzbot,
by guarding the dbMount. As syzbot feeding rubbish into the bmap
descriptor.

Signed-off-by: Hoi Pok Wu <wuhoipok@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index a46fa0f3db571..0ca1ad2610df9 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -211,6 +211,11 @@ int dbMount(struct inode *ipbmap)
 		goto err_release_metapage;
 	}
 
+	if (((bmp->db_mapsize - 1) >> bmp->db_agl2size) > MAXAG) {
+		err = -EINVAL;
+		goto err_release_metapage;
+	}
+
 	for (i = 0; i < MAXAG; i++)
 		bmp->db_agfree[i] = le64_to_cpu(dbmp_le->dn_agfree[i]);
 	bmp->db_agsize = le64_to_cpu(dbmp_le->dn_agsize);