From: Ryoga Saito <contact@xxxxxxxxxxxx> [ Upstream commit 9aca491e0dccf8a9d84a5b478e5eee3c6ea7803b ] This patch fixes kernel NULL pointer dereference when creating nexthop which is bound with SRv6 decapsulation. In the creation of nexthop, __seg6_end_dt_vrf_build is called. __seg6_end_dt_vrf_build expects fc_lninfo in fib6_config is set correctly, but it isn't set in nh_create_ipv6, which causes kernel crash. Here is steps to reproduce kernel crash: 1. modprobe vrf 2. ip -6 nexthop add encap seg6local action End.DT4 vrftable 1 dev eth0 We got the following message: [ 901.370336] BUG: kernel NULL pointer dereference, address: 0000000000000ba0 [ 901.371658] #PF: supervisor read access in kernel mode [ 901.372672] #PF: error_code(0x0000) - not-present page [ 901.373672] PGD 0 P4D 0 [ 901.374248] Oops: 0000 [#1] SMP PTI [ 901.374944] CPU: 0 PID: 8593 Comm: ip Not tainted 5.14-051400-generic #202108310811-Ubuntu [ 901.376404] Hardware name: Red Hat KVM, BIOS 1.11.1-4.module_el8.2.0+320+13f867d7 04/01/2014 [ 901.377907] RIP: 0010:vrf_ifindex_lookup_by_table_id+0x19/0x90 [vrf] [ 901.379182] Code: c1 e9 72 ff ff ff e8 96 49 01 c2 66 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 55 41 89 f5 41 54 53 8b 05 47 4c 00 00 <48> 8b 97 a0 0b 00 00 48 8b 1c c2 e8 57 27 53 c1 4c 8d a3 88 00 00 [ 901.382652] RSP: 0018:ffffbf2d02043590 EFLAGS: 00010282 [ 901.383746] RAX: 000000000000000b RBX: ffff990808255e70 RCX: ffffbf2d02043aa8 [ 901.385436] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000000 [ 901.386924] RBP: ffffbf2d020435b0 R08: 00000000000000c0 R09: ffff990808255e40 [ 901.388537] R10: ffffffff83b08c90 R11: 0000000000000009 R12: 0000000000000000 [ 901.389937] R13: 0000000000000001 R14: 0000000000000000 R15: 000000000000000b [ 901.391226] FS: 00007fe49381f740(0000) GS:ffff99087dc00000(0000) knlGS:0000000000000000 [ 901.392737] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 901.393803] CR2: 0000000000000ba0 CR3: 000000000e3e8003 CR4: 0000000000770ef0 [ 901.395122] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 901.396496] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 901.397833] PKRU: 55555554 [ 901.398578] Call Trace: [ 901.399144] l3mdev_ifindex_lookup_by_table_id+0x3b/0x70 [ 901.400179] __seg6_end_dt_vrf_build+0x34/0xd0 [ 901.401067] seg6_end_dt4_build+0x16/0x20 [ 901.401904] seg6_local_build_state+0x271/0x430 [ 901.402797] lwtunnel_build_state+0x81/0x130 [ 901.403645] fib_nh_common_init+0x82/0x100 [ 901.404465] ? sock_def_readable+0x4b/0x80 [ 901.405285] fib6_nh_init+0x115/0x7c0 [ 901.406033] nh_create_ipv6.isra.0+0xe1/0x140 [ 901.406932] rtm_new_nexthop+0x3b7/0xeb0 [ 901.407828] rtnetlink_rcv_msg+0x152/0x3a0 [ 901.408663] ? rtnl_calcit.isra.0+0x130/0x130 [ 901.409535] netlink_rcv_skb+0x55/0x100 [ 901.410319] rtnetlink_rcv+0x15/0x20 [ 901.411026] netlink_unicast+0x1a8/0x250 [ 901.411813] netlink_sendmsg+0x238/0x470 [ 901.412602] ? _copy_from_user+0x2b/0x60 [ 901.413394] sock_sendmsg+0x65/0x70 [ 901.414112] ____sys_sendmsg+0x218/0x290 [ 901.414929] ? copy_msghdr_from_user+0x5c/0x90 [ 901.415814] ___sys_sendmsg+0x81/0xc0 [ 901.416559] ? fsnotify_destroy_marks+0x27/0xf0 [ 901.417447] ? call_rcu+0xa4/0x230 [ 901.418153] ? kmem_cache_free+0x23f/0x410 [ 901.418972] ? dentry_free+0x37/0x70 [ 901.419705] ? mntput_no_expire+0x4c/0x260 [ 901.420574] __sys_sendmsg+0x62/0xb0 [ 901.421297] __x64_sys_sendmsg+0x1f/0x30 [ 901.422057] do_syscall_64+0x5c/0xc0 [ 901.422756] ? syscall_exit_to_user_mode+0x27/0x50 [ 901.423675] ? __x64_sys_close+0x12/0x40 [ 901.424462] ? do_syscall_64+0x69/0xc0 [ 901.425219] ? irqentry_exit_to_user_mode+0x9/0x20 [ 901.426149] ? irqentry_exit+0x19/0x30 [ 901.426901] ? exc_page_fault+0x89/0x160 [ 901.427709] ? asm_exc_page_fault+0x8/0x30 [ 901.428536] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 901.429514] RIP: 0033:0x7fe493945747 [ 901.430248] Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10 [ 901.433549] RSP: 002b:00007ffe9932cf68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 901.434981] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe493945747 [ 901.436303] RDX: 0000000000000000 RSI: 00007ffe9932cfe0 RDI: 0000000000000003 [ 901.437607] RBP: 00000000613053f7 R08: 0000000000000001 R09: 00007ffe9932d07c [ 901.438990] R10: 000055f4a903a010 R11: 0000000000000246 R12: 0000000000000001 [ 901.440340] R13: 0000000000000001 R14: 000055f4a802b163 R15: 000055f4a8042020 [ 901.441630] Modules linked in: vrf nls_utf8 isofs nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua intel_rapl_msr intel_rapl_common isst_if_mbox_msr isst_if_common nfit rapl input_leds joydev serio_raw qemu_fw_cfg mac_hid sch_fq_codel drm virtio_rng ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel crypto_simd virtio_net net_failover cryptd psmouse virtio_blk failover i2c_piix4 pata_acpi floppy [ 901.450808] CR2: 0000000000000ba0 [ 901.451514] ---[ end trace c27b934b99ade304 ]--- [ 901.452403] RIP: 0010:vrf_ifindex_lookup_by_table_id+0x19/0x90 [vrf] [ 901.453626] Code: c1 e9 72 ff ff ff e8 96 49 01 c2 66 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 55 41 89 f5 41 54 53 8b 05 47 4c 00 00 <48> 8b 97 a0 0b 00 00 48 8b 1c c2 e8 57 27 53 c1 4c 8d a3 88 00 00 [ 901.456910] RSP: 0018:ffffbf2d02043590 EFLAGS: 00010282 [ 901.457912] RAX: 000000000000000b RBX: ffff990808255e70 RCX: ffffbf2d02043aa8 [ 901.459238] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000000 [ 901.460552] RBP: ffffbf2d020435b0 R08: 00000000000000c0 R09: ffff990808255e40 [ 901.461882] R10: ffffffff83b08c90 R11: 0000000000000009 R12: 0000000000000000 [ 901.463208] R13: 0000000000000001 R14: 0000000000000000 R15: 000000000000000b [ 901.464529] FS: 00007fe49381f740(0000) GS:ffff99087dc00000(0000) knlGS:0000000000000000 [ 901.466058] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 901.467189] CR2: 0000000000000ba0 CR3: 000000000e3e8003 CR4: 0000000000770ef0 [ 901.468515] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 901.469858] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 901.471139] PKRU: 55555554 Signed-off-by: Ryoga Saito <contact@xxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/ipv4/nexthop.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c index f5f4369c131c..858bb10d8341 100644 --- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c @@ -1183,6 +1183,7 @@ static int nh_create_ipv4(struct net *net, struct nexthop *nh, .fc_gw4 = cfg->gw.ipv4, .fc_gw_family = cfg->gw.ipv4 ? AF_INET : 0, .fc_flags = cfg->nh_flags, + .fc_nlinfo = cfg->nlinfo, .fc_encap = cfg->nh_encap, .fc_encap_type = cfg->nh_encap_type, }; @@ -1218,6 +1219,7 @@ static int nh_create_ipv6(struct net *net, struct nexthop *nh, .fc_ifindex = cfg->nh_ifindex, .fc_gateway = cfg->gw.ipv6, .fc_flags = cfg->nh_flags, + .fc_nlinfo = cfg->nlinfo, .fc_encap = cfg->nh_encap, .fc_encap_type = cfg->nh_encap_type, }; -- 2.30.2
