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

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Message-ID: <f1a92175-29e1-467a-9334-9d5a9505660a@oracle.com>
Date: Thu, 25 Apr 2024 09:14:09 -0500
From: Dave Kleikamp <dave.kleikamp@...cle.com>
To: Jeongjun Park <aha310510@...il.com>, willy@...radead.org
Cc: brauner@...nel.org, jfs-discussion@...ts.sourceforge.net,
        jlayton@...nel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, shaggy@...nel.org,
        syzbot+241c815bda521982cb49@...kaller.appspotmail.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] jfs: Fix array-index-out-of-bounds in diFree

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);
>