linux-kernel - Re: [PATCH] udf: KASAN: slab-out-of-bounds in udf

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Date:   Tue, 7 Feb 2023 16:17:37 +0300
From:   Ефанов Владислав Александрович <vefanov@...ras.ru>
To:     Jan Kara <jack@...e.cz>
Cc:     Jan Kara <jack@...e.com>, linux-kernel@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: Re: [PATCH] udf: KASAN: slab-out-of-bounds in udf_readdir

Thank you for the information. Will check this repository in the future.

Vlad.

On 07.02.2023 15:44, Jan Kara wrote:
> On Mon 06-02-23 19:22:06, Vladislav Efanov wrote:
>> The KASAN report is:
>> [ 1922.586560] BUG: KASAN: slab-out-of-bounds in udf_readdir+0xe00/0x19e0
>> [ 1922.586922] Write of size 89 at addr ffff888000cd9ea6 by task rm/18493
>>
>> udf_readdir() tries to write file name out of allocated memory
>> buffer bounds. The UDF_NAME_LEN_CS0 (255) is used as max length
>> for file name in udf_put_filename(). But UDF_NAME_LEN (254) is
>> used as the size for buffer allocation in udf_readdir(). As the
>> result out-of-bounds write happened.
>>
>> Found by Linux Verification Center (linuxtesting.org) with xfstests
>>
>> Fixes: 066b9cded00b ("udf: Use separate buffer for copying split names")
>> Signed-off-by: Vladislav Efanov <VEfanov@...ras.ru>
> Thanks for the fix Vladislav! But this code is not there anymore in current
> version of UDF code. It got fixed as part of the directory code rewrite -
> you can check current code state in my tree:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git for_next
>
> 								Honza
>
>> ---
>>   fs/udf/dir.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/udf/dir.c b/fs/udf/dir.c
>> index be640f4b2f2c..b95607c42ad4 100644
>> --- a/fs/udf/dir.c
>> +++ b/fs/udf/dir.c
>> @@ -169,7 +169,7 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
>>   				nameptr = (char *)(fibh.ebh->b_data + poffset - lfi);
>>   			} else {
>>   				if (!copy_name) {
>> -					copy_name = kmalloc(UDF_NAME_LEN,
>> +					copy_name = kmalloc(UDF_NAME_LEN_CS0,
>>   							    GFP_NOFS);
>>   					if (!copy_name) {
>>   						ret = -ENOMEM;
>> -- 
>> 2.34.1
>>