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@xxxxxxxxx> >>> 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@xxxxxxxxx> >>> >>> fs/io-wq.c | 30 ++++++++++++++++++++++-------- >>> 1 file changed, 22 insertions(+), 8 deletions(-) >> >> Does this fix it: >> >> commit 886d0137f104a440d9dfa1d16efc1db06c9a2c02 >> Author: Jens Axboe <axboe@xxxxxxxxx> >> 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
