lkml.org 
[lkml]   [2022]   [May]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [REPORT] Use-after-free Read in __fdget_raw in v5.10.y
From
On 5/17/22 6:24 AM, Lee Jones wrote:
> On Tue, 17 May 2022, Jens Axboe wrote:
>
>> On 5/17/22 5:41 AM, Lee Jones wrote:
>>> Good afternoon Jens, Pavel, et al.,
>>>
>>> Not sure if you are presently aware, but there appears to be a
>>> use-after-free issue affecting the io_uring worker driver (fs/io-wq.c)
>>> in Stable v5.10.y.
>>>
>>> The full sysbot report can be seen below [0].
>>>
>>> The C-reproducer has been placed below that [1].
>>>
>>> I had great success running this reproducer in an infinite loop.
>>>
>>> My colleague reverse-bisected the fixing commit to:
>>>
>>> commit fb3a1f6c745ccd896afadf6e2d6f073e871d38ba
>>> Author: Jens Axboe <axboe@kernel.dk>
>>> Date: Fri Feb 26 09:47:20 2021 -0700
>>>
>>> io-wq: have manager wait for all workers to exit
>>>
>>> Instead of having to wait separately on workers and manager, just have
>>> the manager wait on the workers. We use an atomic_t for the reference
>>> here, as we need to start at 0 and allow increment from that. Since the
>>> number of workers is naturally capped by the allowed nr of processes,
>>> and that uses an int, there is no risk of overflow.
>>>
>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>>
>>> fs/io-wq.c | 30 ++++++++++++++++++++++--------
>>> 1 file changed, 22 insertions(+), 8 deletions(-)
>>
>> Does this fix it:
>>
>> commit 886d0137f104a440d9dfa1d16efc1db06c9a2c02
>> Author: Jens Axboe <axboe@kernel.dk>
>> Date: Fri Mar 5 12:59:30 2021 -0700
>>
>> io-wq: fix race in freeing 'wq' and worker access
>>
>> Looks like it didn't make it into 5.10-stable, but we can certainly
>> rectify that.
>
> Thanks for your quick response Jens.
>
> This patch doesn't apply cleanly to v5.10.y.

This is probably why it never made it into 5.10-stable :-/

> I'll have a go at back-porting it. Please bear with me.

Let me know if you into issues with that and I can help out.

--
Jens Axboe

\
 
 \ /
  Last update: 2022-05-17 14:26    [W:0.354 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site