From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH 5/5] io_uring: fix use after free
Date: Mon, 29 Jun 2020 13:13:03 +0300 [thread overview]
Message-ID: <1221be71ac8977607748d381f90439af4781c1e5.1593424923.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>
After __io_free_req() put a ctx ref, it should assumed that the ctx may
already be gone. However, it can be accessed to put back fallback req.
Free req first and then put a req.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 40996f25822e..013f31e35e78 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1526,12 +1526,15 @@ static void io_dismantle_req(struct io_kiocb *req)
static void __io_free_req(struct io_kiocb *req)
{
+ struct io_ring_ctx *ctx;
+
io_dismantle_req(req);
- percpu_ref_put(&req->ctx->refs);
+ ctx = req->ctx;
if (likely(!io_is_fallback_req(req)))
kmem_cache_free(req_cachep, req);
else
- clear_bit_unlock(0, (unsigned long *) &req->ctx->fallback_req);
+ clear_bit_unlock(0, (unsigned long *) &ctx->fallback_req);
+ percpu_ref_put(&ctx->refs);
}
static bool io_link_cancel_timeout(struct io_kiocb *req)
--
2.24.0
next prev parent reply other threads:[~2020-06-29 20:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-29 10:12 [PATCH 0/5] cleanup for req_free/find_next Pavel Begunkov
2020-06-29 10:12 ` [PATCH 1/5] io_uring: deduplicate freeing linked timeouts Pavel Begunkov
2020-06-29 10:13 ` [PATCH 2/5] io_uring: replace find_next() out param with ret Pavel Begunkov
2020-06-29 10:13 ` [PATCH 3/5] io_uring: kill REQ_F_TIMEOUT Pavel Begunkov
2020-06-29 10:13 ` [PATCH 4/5] io_uring: kill REQ_F_TIMEOUT_NOSEQ Pavel Begunkov
2020-06-29 10:13 ` Pavel Begunkov [this message]
2020-07-03 2:39 ` [PATCH 5/5] io_uring: fix use after free Jann Horn
2020-07-03 19:48 ` Pavel Begunkov
2020-07-03 21:32 ` Jann Horn
2020-07-04 6:49 ` Pavel Begunkov
2020-07-07 12:46 ` Pavel Begunkov
2020-07-07 13:56 ` Jens Axboe
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