2022-10-25 15:57:00

by Hoi Pok Wu

Subject: [PATCH V2] fs: jfs: fix shift-out-of-bounds in dbDiscardAG

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 <[email protected]>
---
V1->2: guarding the corrupted data structure from dbMount instead
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 e1cbfbb60303..765838578a72 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -198,6 +198,11 @@ 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);
--
2.38.1

2022-10-27 22:51:47

by Dave Kleikamp

Subject: Re: [PATCH V2] fs: jfs: fix shift-out-of-bounds in dbDiscardAG

Applied.

Thanks,
Shaggy

On 10/25/22 10:20AM, Hoi Pok Wu wrote:
> 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 <[email protected]>
> ---
> V1->2: guarding the corrupted data structure from dbMount instead
> 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 e1cbfbb60303..765838578a72 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -198,6 +198,11 @@ 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);