On 7/21/2021 2:35 PM, Oliver Hartkopp wrote: > > > On 21.07.21 06:53, Greg KH wrote: >> On Wed, Jul 21, 2021 at 09:09:37AM +0800, Ziyang Xuan wrote: >>> We get a bug during ltp can_filter test as following. >>> >>> =========================================== >>> [60919.264984] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 >>> [60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD 3dda727067 PMD 0 >>> [60919.265443] Oops: 0000 [#1] SMP PTI >>> [60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded Tainted: G W 4.19.90+ #1 > > This kernel version 4.19.90 is definitely outdated. > > Can you please check your issue with the latest uptream kernel as this problem should have been fixed with this patch: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d0caedb759683041d9db82069937525999ada53 > ("can: bcm/raw/isotp: use per module netdevice notifier") > > Thanks! I have tested it under the latest 5.14-rc2 kernel version which includes commit 8d0caedb7596 before I submit the patch. Although I failed to get the vmcore-dmesg file after updating the kernel version to 5.14-rc2 to display here. But we can get the conclusion according to the following debug messages and my problem analysis. ========================================== [ 1048.953574] unlist_netdevice name[vcan0] [ 1048.953661] raw_notify 283: enter, waiting [ 1050.950967] raw_setsockopt 552: ro->bound[1] ro->ifindex[8] sk[ffff9420c5699800] [ 1053.956002] can: receive list entry not found for dev any, id 000, mask 000 [ 1053.961989] can: receive list entry not found for dev vcan0, id 123, mask 7FF raw_setsockopt() executes after unlist_netdevice() and before raw_notify(). The problem always exists. > >>> [60919.266068] RIP: 0010:selinux_socket_sock_rcv_skb+0x3e/0x200 >>> [60919.293289] RSP: 0018:ffff8d53bfc03cf8 EFLAGS: 00010246 >>> [60919.307140] RAX: 0000000000000000 RBX: 000000000000001d RCX: 0000000000000007 >>> [60919.320756] RDX: 0000000000000001 RSI: ffff8d5104a8ed00 RDI: ffff8d53bfc03d30 >>> [60919.334319] RBP: ffff8d9338056800 R08: ffff8d53bfc29d80 R09: 0000000000000001 >>> [60919.347969] R10: ffff8d53bfc03ec0 R11: ffffb8526ef47c98 R12: ffff8d53bfc03d30 >>> [60919.350320] perf: interrupt took too long (3063 > 2500), lowering kernel.perf_event_max_sample_rate to 65000 >>> [60919.361148] R13: 0000000000000001 R14: ffff8d53bcf90000 R15: 0000000000000000 >>> [60919.361151] FS: 00007fb78b6b3600(0000) GS:ffff8d53bfc00000(0000) knlGS:0000000000000000 >>> [60919.400812] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> [60919.413730] CR2: 0000000000000010 CR3: 0000003e3f784006 CR4: 00000000007606e0 >>> [60919.426479] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>> [60919.439339] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>> [60919.451608] PKRU: 55555554 >>> [60919.463622] Call Trace: >>> [60919.475617] <IRQ> >>> [60919.487122] ? update_load_avg+0x89/0x5d0 >>> [60919.498478] ? update_load_avg+0x89/0x5d0 >>> [60919.509822] ? account_entity_enqueue+0xc5/0xf0 >>> [60919.520709] security_sock_rcv_skb+0x2a/0x40 >>> [60919.531413] sk_filter_trim_cap+0x47/0x1b0 >>> [60919.542178] ? kmem_cache_alloc+0x38/0x1b0 >>> [60919.552444] sock_queue_rcv_skb+0x17/0x30 >>> [60919.562477] raw_rcv+0x110/0x190 [can_raw] >>> [60919.572539] can_rcv_filter+0xbc/0x1b0 [can] >>> [60919.582173] can_receive+0x6b/0xb0 [can] >>> [60919.591595] can_rcv+0x31/0x70 [can] >>> [60919.600783] __netif_receive_skb_one_core+0x5a/0x80 >>> [60919.609864] process_backlog+0x9b/0x150 >>> [60919.618691] net_rx_action+0x156/0x400 >>> [60919.627310] ? sched_clock_cpu+0xc/0xa0 >>> [60919.635714] __do_softirq+0xe8/0x2e9 >>> [60919.644161] do_softirq_own_stack+0x2a/0x40 >>> [60919.652154] </IRQ> >>> [60919.659899] do_softirq.part.17+0x4f/0x60 >>> [60919.667475] __local_bh_enable_ip+0x60/0x70 >>> [60919.675089] __dev_queue_xmit+0x539/0x920 >>> [60919.682267] ? finish_wait+0x80/0x80 >>> [60919.689218] ? finish_wait+0x80/0x80 >>> [60919.695886] ? sock_alloc_send_pskb+0x211/0x230 >>> [60919.702395] ? can_send+0xe5/0x1f0 [can] >>> [60919.708882] can_send+0xe5/0x1f0 [can] >>> [60919.715037] raw_sendmsg+0x16d/0x268 [can_raw] >>> >>> It's because raw_setsockopt() concurrently with >>> unregister_netdevice_many(). Concurrent scenario as following. >>> >>> cpu0 cpu1 >>> raw_bind >>> raw_setsockopt unregister_netdevice_many >>> unlist_netdevice >>> dev_get_by_index raw_notifier >>> raw_enable_filters ...... >>> can_rx_register >>> can_rcv_list_find(..., net->can.rx_alldev_list) >>> >>> ...... >>> >>> sock_close >>> raw_release(sock_a) >>> >>> ...... >>> >>> can_receive >>> can_rcv_filter(net->can.rx_alldev_list, ...) >>> raw_rcv(skb, sock_a) >>> BUG >>> >>> After unlist_netdevice(), dev_get_by_index() return NULL in >>> raw_setsockopt(). Function raw_enable_filters() will add sock >>> and can_filter to net->can.rx_alldev_list. Then the sock is closed. >>> Followed by, we sock_sendmsg() to a new vcan device use the same >>> can_filter. Protocol stack match the old receiver whose sock has >>> been released on net->can.rx_alldev_list in can_rcv_filter(). >>> Function raw_rcv() uses the freed sock. UAF BUG is triggered. >>> >>> We can find that the key issue is that net_device has not been >>> protected in raw_setsockopt(). Use rtnl_lock to protect net_device >>> in raw_setsockopt(). >>> >>> Fixes: c18ce101f2e4 ("[CAN]: Add raw protocol") >>> Signed-off-by: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx> >>> --- >>> net/can/raw.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/net/can/raw.c b/net/can/raw.c >>> index ed4fcb7ab0c3..a63e9915c66a 100644 >>> --- a/net/can/raw.c >>> +++ b/net/can/raw.c >>> @@ -546,6 +546,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname, >>> return -EFAULT; >>> } >>> + rtnl_lock(); >>> lock_sock(sk); >>> if (ro->bound && ro->ifindex) >>> @@ -588,6 +589,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname, >>> dev_put(dev); >>> release_sock(sk); >>> + rtnl_unlock(); >>> break; >>> @@ -600,6 +602,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname, >>> err_mask &= CAN_ERR_MASK; >>> + rtnl_lock(); >>> lock_sock(sk); >>> if (ro->bound && ro->ifindex) >>> @@ -627,6 +630,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname, >>> dev_put(dev); >>> release_sock(sk); >>> + rtnl_unlock(); >>> break; >>> -- >>> 2.25.1 >>> >> >> >> <formletter> >> >> This is not the correct way to submit patches for inclusion in the >> stable kernel tree. Please read: >> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html >> for how to do this properly. >> >> </formletter> >> > .
