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  1. 05 Jun, 2023 3 commits
    • Fedor Pchelkin's avatar
      can: j1939: avoid possible use-after-free when j1939_can_rx_register fails · 9f16eb10
      Fedor Pchelkin authored 
      Syzkaller reports the following failure:

BUG: KASAN: use-after-free in kref_put include/linux/kref.h:64 [inline]
BUG: KASAN: use-after-free in j1939_priv_put+0x25/0xa0 net/can/j1939/main.c:172
Write of size 4 at addr ffff888141c15058 by task swapper/3/0

CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.10.144-syzkaller #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 print_address_description.constprop.0+0x1c/0x220 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x145/0x190 mm/kasan/generic.c:192
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline]
 __refcount_sub_and_test include/linux/refcount.h:272 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 kref_put include/linux/kref.h:64 [inline]
 j1939_priv_put+0x25/0xa0 net/can/j1939/main.c:172
 j1939_sk_sock_destruct+0x44/0x90 net/can/j1939/socket.c:374
 __sk_destruct+0x4e/0x820 net/core/sock.c:1784
 rcu_do_batch kernel/rcu/tree.c:2485 [inline]
 rcu_core+0xb35/0x1a30 kernel/rcu/tree.c:2726
 __do_softirq+0x289/0x9a3 kernel/softirq.c:298
 asm_call_irq_on_stack+0x12/0x20
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0xaa/0xe0 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:393 [inline]
 __irq_exit_rcu kernel/softirq.c:423 [inline]
 irq_exit_rcu+0x136/0x200 kernel/softirq.c:435
 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1095
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:635

Allocated by task 1141:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc9/0xd0 mm/kasan/common.c:461
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 j1939_priv_create net/can/j1939/main.c:131 [inline]
 j1939_netdev_start+0x111/0x860 net/can/j1939/main.c:268
 j1939_sk_bind+0x8ea/0xd30 net/can/j1939/socket.c:485
 __sys_bind+0x1f2/0x260 net/socket.c:1645
 __do_sys_bind net/socket.c:1656 [inline]
 __se_sys_bind net/socket.c:1654 [inline]
 __x64_sys_bind+0x6f/0xb0 net/socket.c:1654
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xc6

Freed by task 1141:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0x112/0x170 mm/kasan/common.c:422
 slab_free_hook mm/slub.c:1542 [inline]
 slab_free_freelist_hook+0xad/0x190 mm/slub.c:1576
 slab_free mm/slub.c:3149 [inline]
 kfree+0xd9/0x3b0 mm/slub.c:4125
 j1939_netdev_start+0x5ee/0x860 net/can/j1939/main.c:300
 j1939_sk_bind+0x8ea/0xd30 net/can/j1939/socket.c:485
 __sys_bind+0x1f2/0x260 net/socket.c:1645
 __do_sys_bind net/socket.c:1656 [inline]
 __se_sys_bind net/socket.c:1654 [inline]
 __x64_sys_bind+0x6f/0xb0 net/socket.c:1654
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xc6

It can be caused by this scenario:

CPU0					CPU1
j1939_sk_bind(socket0, ndev0, ...)
  j1939_netdev_start()
					j1939_sk_bind(socket1, ndev0, ...)
                                          j1939_netdev_start()
  mutex_lock(&j1939_netdev_lock)
  j1939_priv_set(ndev0, priv)
  mutex_unlock(&j1939_netdev_lock)
					  if (priv_new)
					    kref_get(&priv_new->rx_kref)
					    return priv_new;
					  /* inside j1939_sk_bind() */
					  jsk->priv = priv
  j1939_can_rx_register(priv) // fails
  j1939_priv_set(ndev, NULL)
  kfree(priv)
					j1939_sk_sock_destruct()
					j1939_priv_put() // <- uaf

To avoid this, call j1939_can_rx_register() under j1939_netdev_lock so
that a concurrent thread cannot process j1939_priv before
j1939_can_rx_register() returns.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 9d71dd0c ("can: add support of SAE J1939 protocol")
Signed-off-by: default avatarFedor Pchelkin <pchelkin@ispras.ru>
Tested-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Acked-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20230526171910.227615-3-pchelkin@ispras.ru
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
      9f16eb10
    • Fedor Pchelkin's avatar
      can: j1939: change j1939_netdev_lock type to mutex · cd9c790d
      Fedor Pchelkin authored 
      It turns out access to j1939_can_rx_register() needs to be serialized,
otherwise j1939_priv can be corrupted when parallel threads call
j1939_netdev_start() and j1939_can_rx_register() fails. This issue is
thoroughly covered in other commit which serializes access to
j1939_can_rx_register().

Change j1939_netdev_lock type to mutex so that we do not need to remove
GFP_KERNEL from can_rx_register().

j1939_netdev_lock seems to be used in normal contexts where mutex usage
is not prohibited.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 9d71dd0c ("can: add support of SAE J1939 protocol")
Suggested-by: default avatarAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: default avatarFedor Pchelkin <pchelkin@ispras.ru>
Tested-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Acked-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20230526171910.227615-2-pchelkin@ispras.ru
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
      cd9c790d
    • Oleksij Rempel's avatar
      can: j1939: j1939_sk_send_loop_abort(): improved error queue handling in J1939 Socket · 2a84aea8
      Oleksij Rempel authored 
      This patch addresses an issue within the j1939_sk_send_loop_abort()
function in the j1939/socket.c file, specifically in the context of
Transport Protocol (TP) sessions.

Without this patch, when a TP session is initiated and a Clear To Send
(CTS) frame is received from the remote side requesting one data packet,
the kernel dispatches the first Data Transport (DT) frame and then waits
for the next CTS. If the remote side doesn't respond with another CTS,
the kernel aborts due to a timeout. This leads to the user-space
receiving an EPOLLERR on the socket, and the socket becomes active.

However, when trying to read the error queue from the socket with
sock.recvmsg(, , socket.MSG_ERRQUEUE), it returns -EAGAIN,
given that the socket is non-blocking. This situation results in an
infinite loop: the user-space repeatedly calls epoll(), epoll() returns
the socket file descriptor with EPOLLERR, but the socket then blocks on
the recv() of ERRQUEUE.

This patch introduces an additional check for the J1939_SOCK_ERRQUEUE
flag within the j1939_sk_send_loop_abort() function. If the flag is set,
it indicates that the application has subscribed to receive error queue
messages. In such cases, the kernel can communicate the current transfer
state via the error queue. This allows for the function to return early,
preventing the unnecessary setting of the socket into an error state,
and breaking the infinite loop. It is crucial to note that a socket
error is only needed if the application isn't using the error queue, as,
without it, the application wouldn't be aware of transfer issues.

Fixes: 9d71dd0c ("can: add support of SAE J1939 protocol")
Reported-by: default avatarDavid Jander <david@protonic.nl>
Tested-by: default avatarDavid Jander <david@protonic.nl>
Signed-off-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20230526081946.715190-1-o.rempel@pengutronix.de
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
      2a84aea8
  3. 04 Jun, 2023 4 commits
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