Messages in this thread | | | Subject | Re: [PATCH 5.13] io_uring: Check current->io_uring in io_uring_cancel_sqpoll | From | Pavel Begunkov <> | Date | Tue, 27 Apr 2021 14:08:23 +0100 |
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On 4/27/21 1:51 PM, Palash Oswal wrote: > syzkaller identified KASAN: null-ptr-deref Write in > io_uring_cancel_sqpoll on v5.12 > > io_uring_cancel_sqpoll is called by io_sq_thread before calling > io_uring_alloc_task_context. This leads to current->io_uring being > NULL. io_uring_cancel_sqpoll should not have to deal with threads > where current->io_uring is NULL. > > In order to cast a wider safety net, perform input sanitisation > directly in io_uring_cancel_sqpoll and return for NULL value of > current->io_uring.
Looks good to me, but better to add a comment why it can be ignored, e.g. "can skip it as it couldn't have submitted requests without tctx"
Also a nit: s/current->io_uring/tctx/
> > Reported-by: syzbot+be51ca5a4d97f017cd50@syzkaller.appspotmail.com > Cc: stable@vger.kernel.org > Signed-off-by: Palash Oswal <hello@oswalpalash.com> > --- > fs/io_uring.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index dff34975d86b..eccad51b7954 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -8998,6 +8998,8 @@ static void io_uring_cancel_sqpoll(struct io_ring_ctx *ctx) > s64 inflight; > DEFINE_WAIT(wait); > > + if (!current->io_uring) > + return; > WARN_ON_ONCE(!sqd || ctx->sq_data->thread != current); > > atomic_inc(&tctx->in_idle); >
-- Pavel Begunkov
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