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Message-ID: <7d795190-339c-4ef7-a1e0-4202a99622f1@gmail.com>
Date: Thu, 3 Oct 2024 22:04:48 +0200
From: Gianfranco Trad <gianf.trad@...il.com>
To: Jan Kara <jack@...e.cz>
Cc: jack@...e.com, linux-kernel@...r.kernel.org, skhan@...uxfoundation.org
Subject: Re: [PATCH v2] udf: fix uninit-value use in udf_get_fileshortad
On 02/10/24 14:29, Jan Kara wrote:
> On Wed 25-09-24 09:46:15, Gianfranco Trad wrote:
>> Check for overflow when computing alen in udf_current_aext to mitigate
>> later uninit-value use in udf_get_fileshortad KMSAN bug[1].
>> After applying the patch reproducer did not trigger any issue[2].
>>
>> [1] https://syzkaller.appspot.com/bug?extid=8901c4560b7ab5c2f9df
>> [2] https://syzkaller.appspot.com/x/log.txt?x=10242227980000
>>
>> Reported-by: syzbot+8901c4560b7ab5c2f9df@...kaller.appspotmail.com
>> Closes: https://syzkaller.appspot.com/bug?extid=8901c4560b7ab5c2f9df
>> Tested-by: syzbot+8901c4560b7ab5c2f9df@...kaller.appspotmail.com
>> Suggested-by: Jan Kara <jack@...e.com>
>> Signed-off-by: Gianfranco Trad <gianf.trad@...il.com>
>
> Thanks. I've added the patch to my tree.
>
> Honza
>
Thanks Jan. This was one of my first patches to the kernel. I will
definitely remember it. Wish you a nice day :)
-- Gian
>> ---
>>
>> Notes:
>> changes in v2:
>> - use check_add_overflow helper to check for overflow.
>>
>> link to v1: https://lore.kernel.org/all/20240919195227.412583-1-gianf.trad@gmail.com/T/
>>
>> fs/udf/inode.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/udf/inode.c b/fs/udf/inode.c
>> index 4726a4d014b6..811a035b600f 100644
>> --- a/fs/udf/inode.c
>> +++ b/fs/udf/inode.c
>> @@ -2215,9 +2215,10 @@ int8_t udf_current_aext(struct inode *inode, struct extent_position *epos,
>> if (!epos->offset)
>> epos->offset = sizeof(struct allocExtDesc);
>> ptr = epos->bh->b_data + epos->offset;
>> - alen = sizeof(struct allocExtDesc) +
>> - le32_to_cpu(((struct allocExtDesc *)epos->bh->b_data)->
>> - lengthAllocDescs);
>> + if (check_add_overflow(sizeof(struct allocExtDesc),
>> + le32_to_cpu(((struct allocExtDesc *)epos->bh->b_data)
>> + ->lengthAllocDescs), &alen))
>> + return -1;
>> }
>>
>> switch (iinfo->i_alloc_type) {
>> --
>> 2.43.0
>>
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