Messages in this thread | | | Date | Tue, 17 May 2022 05:59:29 -0600 | Subject | Re: [REPORT] Use-after-free Read in __fdget_raw in v5.10.y | From | Jens Axboe <> |
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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.
-- Jens Axboe
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