Catching up on long-ignored emails.
On 12/3/24 4:22AM, Edward Adam Davis via Jfs-discussion wrote:
The width in dmapctl of the AG is zero, it trigger a divide error when
calculating the control page level in dbAllocAG.
To avoid this issue, add a check for agwidth in dbAllocAG.
This value shouldn't change unless the filesystem is resized. I would
prefer that the check was made once in dbMount().
Shaggy
Reported-and-tested-by: syzbot+7c808908291a569281a9@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=7c808908291a569281a9
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
---
fs/jfs/jfs_dmap.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index f9009e4f9ffd..2377102d9c4c 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -1373,6 +1373,11 @@ dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
return (rc);
}
+ if (!bmp->db_agwidth) {
+ jfs_error(bmp->db_ipbmap->i_sb, "width in dmapctl of the AG is zero\n");
+ return -EIO;
+ }
+
/* the buffer for the dmap control page that fully describes the
* allocation group.
*/
