Re: [PATCH] jfs: Fix array-index-out-of-bounds in diFree

Matthew Wilcox
2024-04-25T14:17:07Z

On Thu, Apr 25, 2024 at 11:10:38PM +0900, Jeongjun Park wrote:
> Matthew Wilcox wrote:
> > If that's the problem then the correct place to detect & reject this is
> > during mount, not at inode free time.
>
> I fixed the patch as you said. If you patch in this way, the
> file system will not be affected by the vulnerability at all
> due to the code structure.

It should be checked earlier than this. There's this code in
dbMount(). Why isn't this catching it?

bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG ||
bmp->db_agl2size < 0) {
err = -EINVAL;
goto err_release_metapage;
}

if (((bmp->db_mapsize - 1) >> bmp->db_agl2size) > MAXAG) {
err = -EINVAL;
goto err_release_metapage;
}

> Thanks.
>
> ---
> fs/jfs/jfs_imap.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
> index 2ec35889ad24..ba0aa2f145cc 100644
> --- a/fs/jfs/jfs_imap.c
> +++ b/fs/jfs/jfs_imap.c
> @@ -290,7 +290,7 @@ int diSync(struct inode *ipimap)
> int diRead(struct inode *ip)
> {
> struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
> - int iagno, ino, extno, rc;
> + int iagno, ino, extno, rc, agno;
> struct inode *ipimap;
> struct dinode *dp;
> struct iag *iagp;
> @@ -339,6 +339,9 @@ int diRead(struct inode *ip)
>
> /* get the ag for the iag */
> agstart = le64_to_cpu(iagp->agstart);
> + agno = BLKTOAG(agstart, JFS_SBI(ip->i_sb));
> + if(agno >= MAXAG || agno < 0)
> + return -EIO;
>
> release_metapage(mp);
>
> --
> 2.34.1