From cfdbaa3a291d6fd2cb4a1a70d74e63b4abc2f5ec Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Wed, 9 Aug 2023 13:21:41 +0100 Subject: io_uring: fix drain stalls by invalid SQE cq_extra is protected by ->completion_lock, which io_get_sqe() misses. The bug is harmless as it doesn't happen in real life, requires invalid SQ index array and racing with submission, and only messes up the userspace, i.e. stall requests execution but will be cleaned up on ring destruction. Fixes: 15641e427070f ("io_uring: don't cache number of dropped SQEs") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/66096d54651b1a60534bb2023f2947f09f50ef73.1691538547.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- io_uring/io_uring.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'io_uring/io_uring.c') diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 679bea7c41a6..249cab9c86d1 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2374,7 +2374,9 @@ static bool io_get_sqe(struct io_ring_ctx *ctx, const struct io_uring_sqe **sqe) } /* drop invalid entries */ + spin_lock(&ctx->completion_lock); ctx->cq_extra--; + spin_unlock(&ctx->completion_lock); WRITE_ONCE(ctx->rings->sq_dropped, READ_ONCE(ctx->rings->sq_dropped) + 1); return false; -- cgit v1.2.3