Commit 5f5ad9ce authored Sep 18, 2019 by Jackie Liu Committed by Jens Axboe Sep 18, 2019

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: 4fe2c963 ("io_uring: add support for link with drain")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 954dab19

fs/io_uring.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;

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