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From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     Robin van der Gracht <robin@protonic.nl>,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Marc Kleine-Budde <mkl@pengutronix.de>
Cc:     Oleksij Rempel <o.rempel@pengutronix.de>,
        Sili Luo <rootlab@huawei.com>, stable@vger.kernel.org,
        kernel@pengutronix.de, linux-can@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v1] can: j1939: Fix UAF in j1939_sk_match_filter during setsockopt(SO_J1939_FILTER)
Date:   Wed, 27 Sep 2023 18:14:56 +0200
Message-Id: <20230927161456.82772-1-o.rempel@pengutronix.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Lock jsk->sk to prevent UAF when setsockopt(..., SO_J1939_FILTER, ...)
modifies jsk->filters while receiving packets.

Following trace was seen on affected system:
 ==================================================================
 BUG: KASAN: slab-use-after-free in j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939]
 Read of size 4 at addr ffff888012144014 by task j1939/350

 CPU: 0 PID: 350 Comm: j1939 Tainted: G        W  OE      6.5.0-rc5 #1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
 Call Trace:
  print_report+0xd3/0x620
  ? kasan_complete_mode_report_info+0x7d/0x200
  ? j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939]
  kasan_report+0xc2/0x100
  ? j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939]
  __asan_load4+0x84/0xb0
  j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939]
  j1939_sk_recv+0x20b/0x320 [can_j1939]
  ? __kasan_check_write+0x18/0x20
  ? __pfx_j1939_sk_recv+0x10/0x10 [can_j1939]
  ? j1939_simple_recv+0x69/0x280 [can_j1939]
  ? j1939_ac_recv+0x5e/0x310 [can_j1939]
  j1939_can_recv+0x43f/0x580 [can_j1939]
  ? __pfx_j1939_can_recv+0x10/0x10 [can_j1939]
  ? raw_rcv+0x42/0x3c0 [can_raw]
  ? __pfx_j1939_can_recv+0x10/0x10 [can_j1939]
  can_rcv_filter+0x11f/0x350 [can]
  can_receive+0x12f/0x190 [can]
  ? __pfx_can_rcv+0x10/0x10 [can]
  can_rcv+0xdd/0x130 [can]
  ? __pfx_can_rcv+0x10/0x10 [can]
  __netif_receive_skb_one_core+0x13d/0x150
  ? __pfx___netif_receive_skb_one_core+0x10/0x10
  ? __kasan_check_write+0x18/0x20
  ? _raw_spin_lock_irq+0x8c/0xe0
  __netif_receive_skb+0x23/0xb0
  process_backlog+0x107/0x260
  __napi_poll+0x69/0x310
  net_rx_action+0x2a1/0x580
  ? __pfx_net_rx_action+0x10/0x10
  ? __pfx__raw_spin_lock+0x10/0x10
  ? handle_irq_event+0x7d/0xa0
  __do_softirq+0xf3/0x3f8
  do_softirq+0x53/0x80
  </IRQ>
  <TASK>
  __local_bh_enable_ip+0x6e/0x70
  netif_rx+0x16b/0x180
  can_send+0x32b/0x520 [can]
  ? __pfx_can_send+0x10/0x10 [can]
  ? __check_object_size+0x299/0x410
  raw_sendmsg+0x572/0x6d0 [can_raw]
  ? __pfx_raw_sendmsg+0x10/0x10 [can_raw]
  ? apparmor_socket_sendmsg+0x2f/0x40
  ? __pfx_raw_sendmsg+0x10/0x10 [can_raw]
  sock_sendmsg+0xef/0x100
  sock_write_iter+0x162/0x220
  ? __pfx_sock_write_iter+0x10/0x10
  ? __rtnl_unlock+0x47/0x80
  ? security_file_permission+0x54/0x320
  vfs_write+0x6ba/0x750
  ? __pfx_vfs_write+0x10/0x10
  ? __fget_light+0x1ca/0x1f0
  ? __rcu_read_unlock+0x5b/0x280
  ksys_write+0x143/0x170
  ? __pfx_ksys_write+0x10/0x10
  ? __kasan_check_read+0x15/0x20
  ? fpregs_assert_state_consistent+0x62/0x70
  __x64_sys_write+0x47/0x60
  do_syscall_64+0x60/0x90
  ? do_syscall_64+0x6d/0x90
  ? irqentry_exit+0x3f/0x50
  ? exc_page_fault+0x79/0xf0
  entry_SYSCALL_64_after_hwframe+0x6e/0xd8

 Allocated by task 348:
  kasan_save_stack+0x2a/0x50
  kasan_set_track+0x29/0x40
  kasan_save_alloc_info+0x1f/0x30
  __kasan_kmalloc+0xb5/0xc0
  __kmalloc_node_track_caller+0x67/0x160
  j1939_sk_setsockopt+0x284/0x450 [can_j1939]
  __sys_setsockopt+0x15c/0x2f0
  __x64_sys_setsockopt+0x6b/0x80
  do_syscall_64+0x60/0x90
  entry_SYSCALL_64_after_hwframe+0x6e/0xd8

 Freed by task 349:
  kasan_save_stack+0x2a/0x50
  kasan_set_track+0x29/0x40
  kasan_save_free_info+0x2f/0x50
  __kasan_slab_free+0x12e/0x1c0
  __kmem_cache_free+0x1b9/0x380
  kfree+0x7a/0x120
  j1939_sk_setsockopt+0x3b2/0x450 [can_j1939]
  __sys_setsockopt+0x15c/0x2f0
  __x64_sys_setsockopt+0x6b/0x80
  do_syscall_64+0x60/0x90
  entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Fixes: 9d71dd0c70099 ("can: add support of SAE J1939 protocol")
Reported-by: Sili Luo <rootlab@huawei.com>
Suggested-by: Sili Luo <rootlab@huawei.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: stable@vger.kernel.org
---
 net/can/j1939/socket.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index b28c976f52a0..2ce24bf78c72 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -262,12 +262,17 @@ static bool j1939_sk_match_dst(struct j1939_sock *jsk,
 static bool j1939_sk_match_filter(struct j1939_sock *jsk,
 				  const struct j1939_sk_buff_cb *skcb)
 {
-	const struct j1939_filter *f = jsk->filters;
-	int nfilter = jsk->nfilters;
+	const struct j1939_filter *f;
+	int nfilter;
+
+	lock_sock(&jsk->sk);
+
+	f = jsk->filters;
+	nfilter = jsk->nfilters;
 
 	if (!nfilter)
 		/* receive all when no filters are assigned */
-		return true;
+		goto filter_match_found;
 
 	for (; nfilter; ++f, --nfilter) {
 		if ((skcb->addr.pgn & f->pgn_mask) != f->pgn)
@@ -276,9 +281,15 @@ static bool j1939_sk_match_filter(struct j1939_sock *jsk,
 			continue;
 		if ((skcb->addr.src_name & f->name_mask) != f->name)
 			continue;
-		return true;
+		goto filter_match_found;
 	}
+
+	release_sock(&jsk->sk);
 	return false;
+
+filter_match_found:
+	release_sock(&jsk->sk);
+	return true;
 }
 
 static bool j1939_sk_recv_match_one(struct j1939_sock *jsk,
-- 
2.39.2