[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAM_iQpV-QqUJZzvZ4reafkRr3c8uF+R2iW-wFxcEo2R7_etkcg@mail.gmail.com>
Date: Fri, 22 Feb 2019 10:05:57 -0800
From: Cong Wang <xiyou.wangcong@...il.com>
To: Eric Biggers <ebiggers@...nel.org>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
"David S . Miller" <davem@...emloft.net>,
LKML <linux-kernel@...r.kernel.org>,
Mao Wenan <maowenan@...wei.com>,
Lorenzo Colitti <lorenzo@...gle.com>,
Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH net] net: socket: set sock->sk to NULL after calling proto_ops::release()
On Thu, Feb 21, 2019 at 2:14 PM Eric Biggers <ebiggers@...nel.org> wrote:
>
> From: Eric Biggers <ebiggers@...gle.com>
>
> Commit 9060cb719e61 ("net: crypto set sk to NULL when af_alg_release.")
> fixed a use-after-free in sockfs_setattr() when an AF_ALG socket is
> closed concurrently with fchownat(). However, it ignored that many
> other proto_ops::release() methods don't set sock->sk to NULL and
> therefore allow the same use-after-free:
>
> - base_sock_release
> - bnep_sock_release
> - cmtp_sock_release
> - data_sock_release
> - dn_release
> - hci_sock_release
> - hidp_sock_release
> - iucv_sock_release
> - l2cap_sock_release
> - llcp_sock_release
> - llc_ui_release
> - rawsock_release
> - rfcomm_sock_release
> - sco_sock_release
> - svc_release
> - vcc_release
> - x25_release
>
> Rather than fixing all these and relying on every socket type to get
> this right forever, just make __sock_release() set sock->sk to NULL
> itself after calling proto_ops::release().
>
> Reproducer that produces the KASAN splat when any of these socket types
> are configured into the kernel:
>
> #include <pthread.h>
> #include <stdlib.h>
> #include <sys/socket.h>
> #include <unistd.h>
>
> pthread_t t;
> volatile int fd;
>
> void *close_thread(void *arg)
> {
> for (;;) {
> usleep(rand() % 100);
> close(fd);
> }
> }
>
> int main()
> {
> pthread_create(&t, NULL, close_thread, NULL);
> for (;;) {
> fd = socket(rand() % 50, rand() % 11, 0);
> fchownat(fd, "", 1000, 1000, 0x1000);
> close(fd);
> }
> }
>
> Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.")
> Cc: <stable@...r.kernel.org> # v4.10+
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Acked-by: Cong Wang <xiyou.wangcong@...il.com>
Powered by blists - more mailing lists