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

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Message-ID: <ce2b8d4b-7396-43fe-b948-5ab59294832f@arnaud-lcm.com>
Date: Mon, 14 Jul 2025 21:35:01 +0100
From: "Lecomte, Arnaud" <contact@...aud-lcm.com>
To: Dave Kleikamp <dave.kleikamp@...cle.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

Thanks Dave !

On 11/07/2025 20:23, Dave Kleikamp wrote:
> 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,
>
>