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

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Message-ID: <efd5366c-811b-482c-9e69-ce2fe1ef3295@arnaud-lcm.com>
Date: Sun, 27 Jul 2025 10:55:51 +0100
From: Arnaud Lecomte <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

Hi Dave,
I am bumping the thread as I was wondering if you have some updates.
Thanks !

On 14/07/2025 21:35, Lecomte, Arnaud wrote:
> 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,
>>
>>