2023-10-03 18:09:48

by Juntong Deng

Subject: [PATCH] fs/jfs: Add validity check for db_maxag and db_agpref

Both db_maxag and db_agpref are used as the index of the
db_agfree array, but there is currently no validity check for
db_maxag and db_agpref, which can lead to errors.

The following is related bug reported by Syzbot:

UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:639:20
index 7936 is out of range for type 'atomic_t[128]'

Add checking that the values of db_maxag and db_agpref are valid
indexes for the db_agfree array.

Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=38e876a8aa44b7115c76
Signed-off-by: Juntong Deng <[email protected]>
---
fs/jfs/jfs_dmap.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 3a1842348112..4d59373f9e6c 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -195,6 +195,12 @@ int dbMount(struct inode *ipbmap)
bmp->db_maxlevel = le32_to_cpu(dbmp_le->dn_maxlevel);
bmp->db_maxag = le32_to_cpu(dbmp_le->dn_maxag);
bmp->db_agpref = le32_to_cpu(dbmp_le->dn_agpref);
+ if (bmp->db_maxag >= MAXAG || bmp->db_maxag < 0 ||
+ bmp->db_agpref >= MAXAG || bmp->db_agpref < 0) {
+ err = -EINVAL;
+ goto err_release_metapage;
+ }
+
bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
--
2.39.2

2023-10-03 23:44:04

by Dave Kleikamp

Subject: Re: [PATCH] fs/jfs: Add validity check for db_maxag and db_agpref

On 10/3/23 1:06PM, Juntong Deng wrote:
> Both db_maxag and db_agpref are used as the index of the
> db_agfree array, but there is currently no validity check for
> db_maxag and db_agpref, which can lead to errors.
>
> The following is related bug reported by Syzbot:
>
> UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:639:20
> index 7936 is out of range for type 'atomic_t[128]'
>
> Add checking that the values of db_maxag and db_agpref are valid
> indexes for the db_agfree array.

Looks good. Applied.

Thanks,
Shaggy

>
> Reported-by: [email protected]
> Closes: https://syzkaller.appspot.com/bug?extid=38e876a8aa44b7115c76
> Signed-off-by: Juntong Deng <[email protected]>
> ---
> fs/jfs/jfs_dmap.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index 3a1842348112..4d59373f9e6c 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -195,6 +195,12 @@ int dbMount(struct inode *ipbmap)
> bmp->db_maxlevel = le32_to_cpu(dbmp_le->dn_maxlevel);
> bmp->db_maxag = le32_to_cpu(dbmp_le->dn_maxag);
> bmp->db_agpref = le32_to_cpu(dbmp_le->dn_agpref);
> + if (bmp->db_maxag >= MAXAG || bmp->db_maxag < 0 ||
> + bmp->db_agpref >= MAXAG || bmp->db_agpref < 0) {
> + err = -EINVAL;
> + goto err_release_metapage;
> + }
> +
> bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
> bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
> bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);