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

Dave Kleikamp
2024-04-25T14:14:39Z

On 4/25/24 9:10AM, 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.
>
> 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;

That's the right idea, but move the new code after the call to
release_metapage().
>
> release_metapage(mp);
>