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: 2b188cc1bb ("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>
This commit is contained in:
Eric Biggers 2019-06-12 14:58:43 -07:00 committed by Jens Axboe
parent b9aef63aca
commit 355e8d26f7
1 changed files with 3 additions and 1 deletions

View File

@ -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);