Oleg Nesterov oleg@redhat.com wrote:
This is the minimal fix for stable, I'll send cleanups later.
The commit 854a6ed56839a40f6b5d02a2962f48841482eec4 ("signal: Add restore_user_sigmask()") introduced the visible change which breaks user-space: a signal temporary unblocked by set_user_sigmask() can be delivered even if the caller returns success or timeout.
Change restore_user_sigmask() to accept the additional "interrupted" argument which should be used instead of signal_pending() check, and update the callers.
Reported-by: Eric Wong e@80x24.org Fixes: 854a6ed56839a40f6b5d02a2962f48841482eec4 ("signal: Add restore_user_sigmask()") cc: stable@vger.kernel.org (v5.0+) Signed-off-by: Oleg Nesterov oleg@redhat.com
Thanks, for epoll_pwait on top of Linux v5.1.7 and cmogstored v1.7.0:
Tested-by: Eric Wong e@80x24.org
(cmogstored v1.7.1 already works around this when it sees a 0 return value (but not >0, yet...))
diff --git a/fs/io_uring.c b/fs/io_uring.c index 0fbb486..1147c5d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2201,11 +2201,12 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, } ret = wait_event_interruptible(ctx->wait, io_cqring_events(ring) >= min_events);
- if (ret == -ERESTARTSYS)
ret = -EINTR;if (sig)
restore_user_sigmask(sig, &sigsaved);
restore_user_sigmask(sig, &sigsaved, ret == -ERESTARTSYS);- if (ret == -ERESTARTSYS)
ret = -EINTR;return READ_ONCE(ring->r.head) == READ_ONCE(ring->r.tail) ? ret : 0; }
That io_uring bit didn't apply cleanly to stable, since stable is missing fdb288a679cdf6a71f3c1ae6f348ba4dae742681 ("io_uring: use wait_event_interruptible for cq_wait conditional wait") and related commits.
In any case, I'm not using io_uring anywhere, yet (and probably won't, since I'll still need threads to deal with open/unlink/rename on slow JBOD HDDs).