linux-kernel - Re: [Jfs-discussion] [PATCH] jfs: upper bound check of tree index in dbAllocAG

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Message-ID: <e7b79c66-22b4-4d01-be5f-adfc5ba7e50b@oracle.com>
Date: Fri, 11 Jul 2025 14:23:27 -0500
From: Dave Kleikamp <dave.kleikamp@...cle.com>
To: Arnaud Lecomte <contact@...aud-lcm.com>, Dave Kleikamp <shaggy@...nel.org>
Cc: jfs-discussion@...ts.sourceforge.net,
        syzbot+cffd18309153948f3c3e@...kaller.appspotmail.com,
        linux-kernel@...r.kernel.org, skhan@...uxfoundation.org
Subject: Re: [Jfs-discussion] [PATCH] jfs: upper bound check of tree index in
 dbAllocAG

I'm finally trying to catch up.

On 4/23/25 5:13PM, Arnaud Lecomte via Jfs-discussion wrote:
> When computing the tree index in dbAllocAG, we never check we are not
> out of bounds from the size of the stree.
> This could happen in a scenario where the filesystem metadata are
> corrupted.

Looks good. I'll apply and test this.

> 
> Reported-by: syzbot+cffd18309153948f3c3e@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=cffd18309153948f3c3e
> Tested-by: syzbot+cffd18309153948f3c3e@...kaller.appspotmail.com
> Fixes: 263e55949d89 ("x86/cpu/amd: Fix workaround for erratum 1054")

Removing the Fixes: line. This doesn't make sense.

> Signed-off-by: Arnaud Lecomte <contact@...aud-lcm.com>
> ---
>   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 26e89d0c69b6..7acebb9a21b0 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -1385,6 +1385,12 @@ dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
>   	    (1 << (L2LPERCTL - (bmp->db_agheight << 1))) / bmp->db_agwidth;
>   	ti = bmp->db_agstart + bmp->db_agwidth * (agno & (agperlev - 1));
>   
> +	if (ti < 0 || ti >= le32_to_cpu(dcp->nleafs)) {
> +		jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmapctl page: ti out of bounds\n");
> +		release_metapage(mp);
> +		return -EIO;
> +	}
> +
>   	/* dmap control page trees fan-out by 4 and a single allocation
>   	 * group may be described by 1 or 2 subtrees within the ag level
>   	 * dmap control page, depending upon the ag size. examine the ag's
> 
> ---
> base-commit: 8560697b23dc2f405cb463af2b17256a9888129d
> change-id: 20250423-ubsan-jfs-3a58acae5e57
> 
> Best regards,