diff mbox series

[5.7,118/393] io_uring: fix racy overflow count reporting

Message ID 20200817143825.340708318@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH Aug. 17, 2020, 3:12 p.m. UTC 
From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit b2bd1cf99f3e7c8fbf12ea07af2c6998e1209e25 ]

All ->cq_overflow modifications should be under completion_lock,
otherwise it can report a wrong number to the userspace. Fix it in
io_uring_cancel_files().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/io_uring.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 159338b5f8263..c212af69c15b4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7579,10 +7579,9 @@  static void io_uring_cancel_files(struct io_ring_ctx *ctx,
 				clear_bit(0, &ctx->sq_check_overflow);
 				clear_bit(0, &ctx->cq_check_overflow);
 			}
-			spin_unlock_irq(&ctx->completion_lock);
-
 			WRITE_ONCE(ctx->rings->cq_overflow,
 				atomic_inc_return(&ctx->cached_cq_overflow));
+			spin_unlock_irq(&ctx->completion_lock);
 
 			/*
 			 * Put inflight ref and overflow ref. If that's