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* [PATCH for-next 1/1] io_uring/net: fix cleanup double free free_iov init
@ 2022-09-26 13:35 Pavel Begunkov
  2022-09-26 14:37 ` Jens Axboe
  2022-12-19 10:23 ` User-triggerable 6.1 crash [was: io_uring/net: fix cleanup double free free_iov init] Jiri Slaby
  0 siblings, 2 replies; 6+ messages in thread
From: Pavel Begunkov @ 2022-09-26 13:35 UTC (permalink / raw)
  To: io-uring; +Cc: Jens Axboe, asml.silence, syzbot+edfd15cd4246a3fc615a

Having ->async_data doesn't mean it's initialised and previously we vere
relying on setting F_CLEANUP at the right moment. With zc sendmsg
though, we set F_CLEANUP early in prep when we alloc a notif and so we
may allocate async_data, fail in copy_msg_hdr() leaving
struct io_async_msghdr not initialised correctly but with F_CLEANUP
set, which causes a ->free_iov double free and probably other nastiness.

Always initialise ->free_iov. Also, now it might point to fast_iov when
fails, so avoid freeing it during cleanups.

Reported-by: [email protected]
Fixes: 493108d95f146 ("io_uring/net: zerocopy sendmsg")
Signed-off-by: Pavel Begunkov <[email protected]>
---
 io_uring/net.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 2af56661590a..6b69eff6887e 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -124,20 +124,22 @@ static struct io_async_msghdr *io_msg_alloc_async(struct io_kiocb *req,
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct io_cache_entry *entry;
+	struct io_async_msghdr *hdr;
 
 	if (!(issue_flags & IO_URING_F_UNLOCKED) &&
 	    (entry = io_alloc_cache_get(&ctx->netmsg_cache)) != NULL) {
-		struct io_async_msghdr *hdr;
-
 		hdr = container_of(entry, struct io_async_msghdr, cache);
+		hdr->free_iov = NULL;
 		req->flags |= REQ_F_ASYNC_DATA;
 		req->async_data = hdr;
 		return hdr;
 	}
 
-	if (!io_alloc_async_data(req))
-		return req->async_data;
-
+	if (!io_alloc_async_data(req)) {
+		hdr = req->async_data;
+		hdr->free_iov = NULL;
+		return hdr;
+	}
 	return NULL;
 }
 
@@ -192,7 +194,6 @@ int io_send_prep_async(struct io_kiocb *req)
 	io = io_msg_alloc_async_prep(req);
 	if (!io)
 		return -ENOMEM;
-	io->free_iov = NULL;
 	ret = move_addr_to_kernel(zc->addr, zc->addr_len, &io->addr);
 	return ret;
 }
@@ -209,7 +210,6 @@ static int io_setup_async_addr(struct io_kiocb *req,
 	io = io_msg_alloc_async(req, issue_flags);
 	if (!io)
 		return -ENOMEM;
-	io->free_iov = NULL;
 	memcpy(&io->addr, addr_storage, sizeof(io->addr));
 	return -EAGAIN;
 }
@@ -479,7 +479,6 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req,
 
 		if (msg.msg_iovlen == 0) {
 			sr->len = 0;
-			iomsg->free_iov = NULL;
 		} else if (msg.msg_iovlen > 1) {
 			return -EINVAL;
 		} else {
@@ -490,7 +489,6 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req,
 			if (clen < 0)
 				return -EINVAL;
 			sr->len = clen;
-			iomsg->free_iov = NULL;
 		}
 
 		if (req->flags & REQ_F_APOLL_MULTISHOT) {
@@ -913,7 +911,9 @@ void io_send_zc_cleanup(struct io_kiocb *req)
 
 	if (req_has_async_data(req)) {
 		io = req->async_data;
-		kfree(io->free_iov);
+		/* might be ->fast_iov if *msg_copy_hdr failed */
+		if (io->free_iov != io->fast_iov)
+			kfree(io->free_iov);
 	}
 	if (zc->notif) {
 		zc->notif->flags |= REQ_F_CQE_SKIP;
-- 
2.37.2


^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-12-19 13:43 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-09-26 13:35 [PATCH for-next 1/1] io_uring/net: fix cleanup double free free_iov init Pavel Begunkov
2022-09-26 14:37 ` Jens Axboe
2022-12-19 10:23 ` User-triggerable 6.1 crash [was: io_uring/net: fix cleanup double free free_iov init] Jiri Slaby
2022-12-19 12:32   ` Jiri Slaby
2022-12-19 13:42     ` Pavel Begunkov
2022-12-19 13:41   ` Jens Axboe

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