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From:   Dongliang Mu <dzm91@hust.edu.cn>
To:     Dave Kleikamp <shaggy@kernel.org>,
        Dongliang Mu <dzm91@hust.edu.cn>,
        Zixuan Fu <r33s3n6@gmail.com>,
        Pavel Skripkin <paskripkin@gmail.com>
Cc:     kernel test robot <lkp@intel.com>,
        Dave Kleikamp <dave.kleikamp@oracle.com>,
        jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: [PATCH] fs: jfs: use the correct value to do sanity check
Date:   Tue, 18 Oct 2022 16:33:43 +0800
Message-Id: <20221018083346.855584-1-dzm91@hust.edu.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The previous commit 920f4b7e923b ("fs: jfs: fix shift-out-of-bounds
in dbAllocAG") incorrectly uses MAXMAPSIZE - L2MAXAG as upper bound to
limit bmp->db_agl2size. The right value should be L2MAXL2SIZE - L2MAXAG,
i.e., 13 + 10*3 - 7 = 36, according to Dave Kleikamp.

Fix this by modifying the upper bound to the correct value.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 920f4b7e923b ("fs: jfs: fix shift-out-of-bounds in dbAllocAG")
Signed-off-by: Dongliang Mu <dzm91@hust.edu.cn>
---
 fs/jfs/jfs_dmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 962c855631cb..e1cbfbb60303 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -193,7 +193,7 @@ 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 > MAXMAPSIZE - L2MAXAG) {
+	if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG) {
 		err = -EINVAL;
 		goto err_release_metapage;
 	}
-- 
2.35.1