lkml.org 
[lkml]   [2020]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v1] qnx4_match: do not over run the buffer
From
Date
Thanks for the clarification! This sounds good to me.
I will send a revised patch.
Best,
- Tong

> On Nov 21, 2020, at 4:57 PM, Anders Larsen <al@alarsen.net> wrote:
>
> On Saturday, 2020-11-21 22:47 Tong Zhang wrote:
>>
>>> 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 QNX4_FILE_LINK is set in de->di_status (see line 38), 'de' actually points to a struct qnx4_link_info which can hold a longer name.
> That's the reason for the namelen massage.
> (Please don't ask why it is not a union)
>
> Cheers
> Anders
>
>

\
 
 \ /
  Last update: 2020-11-22 02:28    [W:0.046 / U:0.212 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site