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. Reported-by: syzbot+be51ca5a4d97f017cd50@xxxxxxxxxxxxxxxxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Palash Oswal <hello@xxxxxxxxxxxxxxx> --- 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); -- 2.27.0
