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io_uring/cancel: re-grab ctx mutex after finishing wait

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If we have a signal pending during cancelations, it'll cause the
task_work run to return an error. Since we didn't run task_work, the
current task is left in TASK_INTERRUPTIBLE state when we need to
re-grab the ctx mutex, and the kernel will rightfully complain about
that.

Move the lock grabbing for the error cases outside the loop to avoid
that issue.

Reported-by: syzbot+7df055631cd1be4586fd@syzkaller.appspotmail.com
Link: https://lore.kernel.org/io-uring/0000000000003a14a905f05050b0@google.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2022-12-21 07:11:33 -07:00
parent 52ea806ad9
commit 23fffb2f09
1 changed files with 4 additions and 5 deletions
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9
io_uring/cancel.c
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@ -288,24 +288,23 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg)
ret = __io_sync_cancel(current->io_uring, &cd, sc.fd);
mutex_unlock(&ctx->uring_lock);
if (ret != -EALREADY)
break;
mutex_unlock(&ctx->uring_lock);
ret = io_run_task_work_sig(ctx);
if (ret < 0) {
mutex_lock(&ctx->uring_lock);
if (ret < 0)
break;
}
ret = schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS);
mutex_lock(&ctx->uring_lock);
if (!ret) {
ret = -ETIME;
break;
}
mutex_lock(&ctx->uring_lock);
} while (1);
finish_wait(&ctx->cq_wait, &wait);
mutex_lock(&ctx->uring_lock);
if (ret == -ENOENT || ret > 0)
ret = 0;