From 5f5ad9ced33621d353be6429c3900f8a526fcae8 Mon Sep 17 00:00:00 2001 From: Jackie Liu Date: Wed, 18 Sep 2019 10:37:53 +0800 Subject: [PATCH] io_uring: fix use-after-free of shadow_req There is a potential dangling pointer problem. we never clean shadow_req, if there are multiple link lists in this series of sqes, then the shadow_req will not reallocate, and continue to use the last one. but in the previous, his memory has been released, thus forming a dangling pointer. let's clean up him and make sure that every new link list can reapply for a new shadow_req. Fixes: 4fe2c963154c ("io_uring: add support for link with drain") Signed-off-by: Jackie Liu Signed-off-by: Jens Axboe --- fs/io_uring.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/io_uring.c b/fs/io_uring.c index 42a684ef578a..1621243da1ea 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2357,6 +2357,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes, io_queue_link_head(ctx, link, &link->submit, shadow_req, true); link = NULL; + shadow_req = NULL; } prev_was_link = (sqes[i].sqe->flags & IOSQE_IO_LINK) != 0; @@ -2543,6 +2544,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit, io_queue_link_head(ctx, link, &link->submit, shadow_req, force_nonblock); link = NULL; + shadow_req = NULL; } prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;