From 355e8d26f719c207aa2e00e6f3cfab3acf21769b Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Wed, 12 Jun 2019 14:58:43 -0700
Subject: [PATCH] io_uring: fix memory leak of UNIX domain socket inode
Opening and closing an io_uring instance leaks a UNIX domain socket
inode. This is because the ->file of the io_uring instance's internal
UNIX domain socket is set to point to the io_uring file, but then
sock_release() sees the non-NULL ->file and assumes the inode reference
is held by the file so doesn't call iput(). That's not the case here,
since the reference is still meant to be held by the socket; the actual
inode of the io_uring file is different.
Fix this leak by NULL-ing out ->file before releasing the socket.
Reported-by: syzbot+111cb28d9f583693aefa@syzkaller.appspotmail.com
Fixes: 2b188cc1bb85 ("Add io_uring IO interface")
Cc: <stable@vger.kernel.org> # v5.1+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0fbb486a320e9..86a2bd7219005 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2777,8 +2777,10 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
io_eventfd_unregister(ctx);
#if defined(CONFIG_UNIX)
- if (ctx->ring_sock)
+ if (ctx->ring_sock) {
+ ctx->ring_sock->file = NULL; /* so that iput() is called */
sock_release(ctx->ring_sock);
+ }
#endif
io_mem_free(ctx->sq_ring);
--
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