5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Andy Roulin <aroulin@xxxxxxxxxx>
[ Upstream commit f9ff7665cd128012868098bbd07e28993e314fdb ]
Fix a kernel panic in the br_netfilter module when sending untagged
traffic via a VxLAN device.
This happens during the check for fragmentation in br_nf_dev_queue_xmit.
It is dependent on:
1) the br_netfilter module being loaded;
2) net.bridge.bridge-nf-call-iptables set to 1;
3) a bridge with a VxLAN (single-vxlan-device) netdevice as a bridge port;
4) untagged frames with size higher than the VxLAN MTU forwarded/flooded
When forwarding the untagged packet to the VxLAN bridge port, before
the netfilter hooks are called, br_handle_egress_vlan_tunnel is called and
changes the skb_dst to the tunnel dst. The tunnel_dst is a metadata type
of dst, i.e., skb_valid_dst(skb) is false, and metadata->dst.dev is NULL.
Then in the br_netfilter hooks, in br_nf_dev_queue_xmit, there's a check
for frames that needs to be fragmented: frames with higher MTU than the
VxLAN device end up calling br_nf_ip_fragment, which in turns call
ip_skb_dst_mtu.
The ip_dst_mtu tries to use the skb_dst(skb) as if it was a valid dst
with valid dst->dev, thus the crash.
This case was never supported in the first place, so drop the packet
instead.
PING 10.0.0.2 (10.0.0.2) from 0.0.0.0 h1-eth0: 2000(2028) bytes of data.
[ 176.291791] Unable to handle kernel NULL pointer dereference at
virtual address 0000000000000110
[ 176.292101] Mem abort info:
[ 176.292184] ESR = 0x0000000096000004
[ 176.292322] EC = 0x25: DABT (current EL), IL = 32 bits
[ 176.292530] SET = 0, FnV = 0
[ 176.292709] EA = 0, S1PTW = 0
[ 176.292862] FSC = 0x04: level 0 translation fault
[ 176.293013] Data abort info:
[ 176.293104] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[ 176.293488] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 176.293787] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 176.293995] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000043ef5000
[ 176.294166] [0000000000000110] pgd=0000000000000000,
p4d=0000000000000000
[ 176.294827] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[ 176.295252] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel veth
br_netfilter bridge stp llc ipv6 crct10dif_ce
[ 176.295923] CPU: 0 PID: 188 Comm: ping Not tainted
6.8.0-rc3-g5b3fbd61b9d1 #2
[ 176.296314] Hardware name: linux,dummy-virt (DT)
[ 176.296535] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS
BTYPE=--)
[ 176.296808] pc : br_nf_dev_queue_xmit+0x390/0x4ec [br_netfilter]
[ 176.297382] lr : br_nf_dev_queue_xmit+0x2ac/0x4ec [br_netfilter]
[ 176.297636] sp : ffff800080003630
[ 176.297743] x29: ffff800080003630 x28: 0000000000000008 x27:
ffff6828c49ad9f8
[ 176.298093] x26: ffff6828c49ad000 x25: 0000000000000000 x24:
00000000000003e8
[ 176.298430] x23: 0000000000000000 x22: ffff6828c4960b40 x21:
ffff6828c3b16d28
[ 176.298652] x20: ffff6828c3167048 x19: ffff6828c3b16d00 x18:
0000000000000014
[ 176.298926] x17: ffffb0476322f000 x16: ffffb7e164023730 x15:
0000000095744632
[ 176.299296] x14: ffff6828c3f1c880 x13: 0000000000000002 x12:
ffffb7e137926a70
[ 176.299574] x11: 0000000000000001 x10: ffff6828c3f1c898 x9 :
0000000000000000
[ 176.300049] x8 : ffff6828c49bf070 x7 : 0008460f18d5f20e x6 :
f20e0100bebafeca
[ 176.300302] x5 : ffff6828c7f918fe x4 : ffff6828c49bf070 x3 :
0000000000000000
[ 176.300586] x2 : 0000000000000000 x1 : ffff6828c3c7ad00 x0 :
ffff6828c7f918f0
[ 176.300889] Call trace:
[ 176.301123] br_nf_dev_queue_xmit+0x390/0x4ec [br_netfilter]
[ 176.301411] br_nf_post_routing+0x2a8/0x3e4 [br_netfilter]
[ 176.301703] nf_hook_slow+0x48/0x124
[ 176.302060] br_forward_finish+0xc8/0xe8 [bridge]
[ 176.302371] br_nf_hook_thresh+0x124/0x134 [br_netfilter]
[ 176.302605] br_nf_forward_finish+0x118/0x22c [br_netfilter]
[ 176.302824] br_nf_forward_ip.part.0+0x264/0x290 [br_netfilter]
[ 176.303136] br_nf_forward+0x2b8/0x4e0 [br_netfilter]
[ 176.303359] nf_hook_slow+0x48/0x124
[ 176.303803] __br_forward+0xc4/0x194 [bridge]
[ 176.304013] br_flood+0xd4/0x168 [bridge]
[ 176.304300] br_handle_frame_finish+0x1d4/0x5c4 [bridge]
[ 176.304536] br_nf_hook_thresh+0x124/0x134 [br_netfilter]
[ 176.304978] br_nf_pre_routing_finish+0x29c/0x494 [br_netfilter]
[ 176.305188] br_nf_pre_routing+0x250/0x524 [br_netfilter]
[ 176.305428] br_handle_frame+0x244/0x3cc [bridge]
[ 176.305695] __netif_receive_skb_core.constprop.0+0x33c/0xecc
[ 176.306080] __netif_receive_skb_one_core+0x40/0x8c
[ 176.306197] __netif_receive_skb+0x18/0x64
[ 176.306369] process_backlog+0x80/0x124
[ 176.306540] __napi_poll+0x38/0x17c
[ 176.306636] net_rx_action+0x124/0x26c
[ 176.306758] __do_softirq+0x100/0x26c
[ 176.307051] ____do_softirq+0x10/0x1c
[ 176.307162] call_on_irq_stack+0x24/0x4c
[ 176.307289] do_softirq_own_stack+0x1c/0x2c
[ 176.307396] do_softirq+0x54/0x6c
[ 176.307485] __local_bh_enable_ip+0x8c/0x98
[ 176.307637] __dev_queue_xmit+0x22c/0xd28
[ 176.307775] neigh_resolve_output+0xf4/0x1a0
[ 176.308018] ip_finish_output2+0x1c8/0x628
[ 176.308137] ip_do_fragment+0x5b4/0x658
[ 176.308279] ip_fragment.constprop.0+0x48/0xec
[ 176.308420] __ip_finish_output+0xa4/0x254
[ 176.308593] ip_finish_output+0x34/0x130
[ 176.308814] ip_output+0x6c/0x108
[ 176.308929] ip_send_skb+0x50/0xf0
[ 176.309095] ip_push_pending_frames+0x30/0x54
[ 176.309254] raw_sendmsg+0x758/0xaec
[ 176.309568] inet_sendmsg+0x44/0x70
[ 176.309667] __sys_sendto+0x110/0x178
[ 176.309758] __arm64_sys_sendto+0x28/0x38
[ 176.309918] invoke_syscall+0x48/0x110
[ 176.310211] el0_svc_common.constprop.0+0x40/0xe0
[ 176.310353] do_el0_svc+0x1c/0x28
[ 176.310434] el0_svc+0x34/0xb4
[ 176.310551] el0t_64_sync_handler+0x120/0x12c
[ 176.310690] el0t_64_sync+0x190/0x194
[ 176.311066] Code: f9402e61 79402aa2 927ff821 f9400023 (f9408860)
[ 176.315743] ---[ end trace 0000000000000000 ]---
[ 176.316060] Kernel panic - not syncing: Oops: Fatal exception in
interrupt
[ 176.316371] Kernel Offset: 0x37e0e3000000 from 0xffff800080000000
[ 176.316564] PHYS_OFFSET: 0xffff97d780000000
[ 176.316782] CPU features: 0x0,88000203,3c020000,0100421b
[ 176.317210] Memory Limit: none
[ 176.317527] ---[ end Kernel panic - not syncing: Oops: Fatal
Exception in interrupt ]---\
Fixes: 11538d039ac6 ("bridge: vlan dst_metadata hooks in ingress and egress paths")
Reviewed-by: Ido Schimmel <idosch@xxxxxxxxxx>
Signed-off-by: Andy Roulin <aroulin@xxxxxxxxxx>
Acked-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20241001154400.22787-2-aroulin@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/bridge/br_netfilter_hooks.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 277b6fb92ac5f..a16559140541c 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -33,6 +33,7 @@
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/addrconf.h>
+#include <net/dst_metadata.h>
#include <net/route.h>
#include <net/netfilter/br_netfilter.h>
#include <net/netns/generic.h>
@@ -753,6 +754,10 @@ static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff
return br_dev_queue_push_xmit(net, sk, skb);
}
+ /* Fragmentation on metadata/template dst is not supported */
+ if (unlikely(!skb_valid_dst(skb)))
+ goto drop;
+
/* This is wrong! We should preserve the original fragment
* boundaries by preserving frag_list rather than refragmenting.
*/
--
2.43.0
