We should not assume anything about ->free_iov just from
REQ_F_ASYNC_DATA but rather rely on REQ_F_NEED_CLEANUP, as we may
allocate ->async_data but failed init would leave the field in not
consistent state. The easiest solution is to remove removing
REQ_F_NEED_CLEANUP and so ->async_data dealloc from io_sendrecv_fail()
and let io_send_zc_cleanup() do the job. The catch here is that we also
need to prevent double notif flushing, just test it for NULL and zero
where it's needed.
BUG: KASAN: use-after-free in io_sendrecv_fail+0x3b0/0x3e0 io_uring/net.c:1221
Write of size 8 at addr ffff8880771b4080 by task syz-executor.3/30199
CPU: 1 PID: 30199 Comm: syz-executor.3 Not tainted 6.0.0-rc6-next-20220923-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:395
kasan_report+0xbb/0x1f0 mm/kasan/report.c:495
io_sendrecv_fail+0x3b0/0x3e0 io_uring/net.c:1221
io_req_complete_failed+0x155/0x1b0 io_uring/io_uring.c:873
io_drain_req io_uring/io_uring.c:1648 [inline]
io_queue_sqe_fallback.cold+0x29f/0x788 io_uring/io_uring.c:1931
io_submit_sqe io_uring/io_uring.c:2160 [inline]
io_submit_sqes+0x1180/0x1df0 io_uring/io_uring.c:2276
__do_sys_io_uring_enter+0xac6/0x2410 io_uring/io_uring.c:3216
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: c4c0009e0b56e ("io_uring/net: combine fail handlers")
Reported-by: syzbot+4c597a574a3f5a251bda@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
io_uring/net.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
diff --git a/io_uring/net.c b/io_uring/net.c
index 757a300578f4..e9e66bace45f 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -915,9 +915,11 @@ void io_send_zc_cleanup(struct io_kiocb *req)
io = req->async_data;
kfree(io->free_iov);
}
- zc->notif->flags |= REQ_F_CQE_SKIP;
- io_notif_flush(zc->notif);
- zc->notif = NULL;
+ if (zc->notif) {
+ zc->notif->flags |= REQ_F_CQE_SKIP;
+ io_notif_flush(zc->notif);
+ zc->notif = NULL;
+ }
}
int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
@@ -1215,12 +1217,6 @@ void io_sendrecv_fail(struct io_kiocb *req)
io_notif_flush(sr->notif);
sr->notif = NULL;
}
- if (req_has_async_data(req)) {
- io = req->async_data;
- kfree(io->free_iov);
- io->free_iov = NULL;
- }
- req->flags &= ~REQ_F_NEED_CLEANUP;
io_req_set_res(req, res, req->cqe.flags);
}
--
2.37.2
