From: Tong Zhang <ztong0001@gmail.com>
To: Anders Larsen <al@alarsen.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] qnx4_match: do not over run the buffer
Date: Sat, 21 Nov 2020 16:47:24 -0500 [thread overview]
Message-ID: <E554952E-602B-4711-BEF1-FB3398DA7225@gmail.com> (raw)
In-Reply-To: <2474566.rpppqFFLNx@alarsen.net>
> On Nov 21, 2020, at 4:40 PM, Anders Larsen <al@alarsen.net> wrote:
>
> On Friday, 2020-11-20 22:21 Tong Zhang wrote:
>> the di_fname may not terminated by '\0', use strnlen to prevent buffer
>> overrun
>>
>> ---
>> fs/qnx4/namei.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/qnx4/namei.c b/fs/qnx4/namei.c
>> index 8d72221735d7..c0e79094f578 100644
>> --- a/fs/qnx4/namei.c
>> +++ b/fs/qnx4/namei.c
>> @@ -40,7 +40,7 @@ static int qnx4_match(int len, const char *name,
>> } else {
>> namelen = QNX4_SHORT_NAME_MAX;
>> }
>> - thislen = strlen( de->di_fname );
>> + thislen = strnlen( de->di_fname, QNX4_SHORT_NAME_MAX );
>
> that should be
> + thislen = strnlen( de->di_fname, namelen );
> otherwise the length of a filename would always be limited to QNX4_SHORT_NAME_MAX (16) characters.
>
Why should we put something bigger here if the size of qnx4_inode_entry->di_fname is QNX4_SHORT_NAME_MAX.
Won’t that be a problem?
>> if ( thislen > namelen )
>> thislen = namelen;
>
> These two lines can be dropped now, as the result of strnlen() cannot exceed namelen anyway.
>
> Cheers
> Anders
>
>
next prev parent reply other threads:[~2020-11-21 21:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 21:21 [PATCH v1] qnx4_match: do not over run the buffer Tong Zhang
2020-11-21 21:40 ` Anders Larsen
2020-11-21 21:47 ` Tong Zhang [this message]
2020-11-21 21:57 ` Anders Larsen
2020-11-22 1:27 ` Tong Zhang
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