struct layout randomization for Clang #57
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Sep 10, 2019
Hangbin Liu says:
====================
fix dev null pointer dereference when send packets larger than mtu in collect_md mode
When we send a packet larger than PMTU, we need to reply with
icmp_send(ICMP_FRAG_NEEDED) or icmpv6_send(ICMPV6_PKT_TOOBIG).
But with collect_md mode, kernel will crash while accessing the dst dev
as __metadata_dst_init() init dst->dev to NULL by default. Here is what
the code path looks like, for GRE:
- ip6gre_tunnel_xmit
- ip6gre_xmit_ipv4
- __gre6_xmit
- ip6_tnl_xmit
- if skb->len - t->tun_hlen - eth_hlen > mtu; return -EMSGSIZE
- icmp_send
- net = dev_net(rt->dst.dev); <-- here
- ip6gre_xmit_ipv6
- __gre6_xmit
- ip6_tnl_xmit
- if skb->len - t->tun_hlen - eth_hlen > mtu; return -EMSGSIZE
- icmpv6_send
...
- decode_session4
- oif = skb_dst(skb)->dev->ifindex; <-- here
- decode_session6
- oif = skb_dst(skb)->dev->ifindex; <-- here
We could not fix it in __metadata_dst_init() as there is no dev supplied.
Look in to the __icmp_send()/decode_session{4,6} code we could find the dst
dev is actually not needed. In __icmp_send(), we could get the net by skb->dev.
For decode_session{4,6}, as it was called by xfrm_decode_session_reverse()
in this scenario, the oif is not used by
fl4->flowi4_oif = reverse ? skb->skb_iif : oif;
The reproducer is easy:
ovs-vsctl add-br br0
ip link set br0 up
ovs-vsctl add-port br0 gre0 -- set interface gre0 type=gre options:remote_ip=$dst_addr
ip link set gre0 up
ip addr add ${local_gre6}/64 dev br0
ping6 $remote_gre6 -s 1500
The kernel will crash like
[40595.821651] BUG: kernel NULL pointer dereference, address: 0000000000000108
[40595.822411] #PF: supervisor read access in kernel mode
[40595.822949] #PF: error_code(0x0000) - not-present page
[40595.823492] PGD 0 P4D 0
[40595.823767] Oops: 0000 [GrapheneOS#1] SMP PTI
[40595.824139] CPU: 0 PID: 2831 Comm: handler12 Not tainted 5.2.0 GrapheneOS#57
[40595.824788] Hardware name: Red Hat KVM, BIOS 1.11.1-3.module+el8.1.0+2983+b2ae9c0a 04/01/2014
[40595.825680] RIP: 0010:__xfrm_decode_session+0x6b/0x930
[40595.826219] Code: b7 c0 00 00 00 b8 06 00 00 00 66 85 d2 0f b7 ca 48 0f 45 c1 44 0f b6 2c 06 48 8b 47 58 48 83 e0 fe 0f 84 f4 04 00 00 48 8b 00 <44> 8b 80 08 01 00 00 41 f6 c4 01 4c 89 e7
ba 58 00 00 00 0f 85 47
[40595.828155] RSP: 0018:ffffc90000a73438 EFLAGS: 00010286
[40595.828705] RAX: 0000000000000000 RBX: ffff8881329d7100 RCX: 0000000000000000
[40595.829450] RDX: 0000000000000000 RSI: ffff8881339e70ce RDI: ffff8881329d7100
[40595.830191] RBP: ffffc90000a73470 R08: 0000000000000000 R09: 000000000000000a
[40595.830936] R10: 0000000000000000 R11: 0000000000000000 R12: ffffc90000a73490
[40595.831682] R13: 000000000000002c R14: ffff888132ff1301 R15: ffff8881329d7100
[40595.832427] FS: 00007f5bfcfd6700(0000) GS:ffff88813ba00000(0000) knlGS:0000000000000000
[40595.833266] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[40595.833883] CR2: 0000000000000108 CR3: 000000013a368000 CR4: 00000000000006f0
[40595.834633] Call Trace:
[40595.835392] ? rt6_multipath_hash+0x4c/0x390
[40595.835853] icmpv6_route_lookup+0xcb/0x1d0
[40595.836296] ? icmpv6_xrlim_allow+0x3e/0x140
[40595.836751] icmp6_send+0x537/0x840
[40595.837125] icmpv6_send+0x20/0x30
[40595.837494] tnl_update_pmtu.isra.27+0x19d/0x2a0 [ip_tunnel]
[40595.838088] ip_md_tunnel_xmit+0x1b6/0x510 [ip_tunnel]
[40595.838633] gre_tap_xmit+0x10c/0x160 [ip_gre]
[40595.839103] dev_hard_start_xmit+0x93/0x200
[40595.839551] sch_direct_xmit+0x101/0x2d0
[40595.839967] __dev_queue_xmit+0x69f/0x9c0
[40595.840399] do_execute_actions+0x1717/0x1910 [openvswitch]
[40595.840987] ? validate_set.isra.12+0x2f5/0x3d0 [openvswitch]
[40595.841596] ? reserve_sfa_size+0x31/0x130 [openvswitch]
[40595.842154] ? __ovs_nla_copy_actions+0x1b4/0xad0 [openvswitch]
[40595.842778] ? __kmalloc_reserve.isra.50+0x2e/0x80
[40595.843285] ? should_failslab+0xa/0x20
[40595.843696] ? __kmalloc+0x188/0x220
[40595.844078] ? __alloc_skb+0x97/0x270
[40595.844472] ovs_execute_actions+0x47/0x120 [openvswitch]
[40595.845041] ovs_packet_cmd_execute+0x27d/0x2b0 [openvswitch]
[40595.845648] genl_family_rcv_msg+0x3a8/0x430
[40595.846101] genl_rcv_msg+0x47/0x90
[40595.846476] ? __alloc_skb+0x83/0x270
[40595.846866] ? genl_family_rcv_msg+0x430/0x430
[40595.847335] netlink_rcv_skb+0xcb/0x100
[40595.847777] genl_rcv+0x24/0x40
[40595.848113] netlink_unicast+0x17f/0x230
[40595.848535] netlink_sendmsg+0x2ed/0x3e0
[40595.848951] sock_sendmsg+0x4f/0x60
[40595.849323] ___sys_sendmsg+0x2bd/0x2e0
[40595.849733] ? sock_poll+0x6f/0xb0
[40595.850098] ? ep_scan_ready_list.isra.14+0x20b/0x240
[40595.850634] ? _cond_resched+0x15/0x30
[40595.851032] ? ep_poll+0x11b/0x440
[40595.851401] ? _copy_to_user+0x22/0x30
[40595.851799] __sys_sendmsg+0x58/0xa0
[40595.852180] do_syscall_64+0x5b/0x190
[40595.852574] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[40595.853105] RIP: 0033:0x7f5c00038c7d
[40595.853489] Code: c7 20 00 00 75 10 b8 2e 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 8e f7 ff ff 48 89 04 24 b8 2e 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 d7 f7 ff ff 48 89
d0 48 83 c4 08 48 3d 01
[40595.855443] RSP: 002b:00007f5bfcf73c00 EFLAGS: 00003293 ORIG_RAX: 000000000000002e
[40595.856244] RAX: ffffffffffffffda RBX: 00007f5bfcf74a60 RCX: 00007f5c00038c7d
[40595.856990] RDX: 0000000000000000 RSI: 00007f5bfcf73c60 RDI: 0000000000000015
[40595.857736] RBP: 0000000000000004 R08: 0000000000000b7c R09: 0000000000000110
[40595.858613] R10: 0001000800050004 R11: 0000000000003293 R12: 000055c2d8329da0
[40595.859401] R13: 00007f5bfcf74120 R14: 0000000000000347 R15: 00007f5bfcf73c60
[40595.860185] Modules linked in: ip_gre ip_tunnel gre openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 sunrpc bochs_drm ttm drm_kms_helper drm pcspkr joydev i2c_piix4 qemu_fw_cfg xfs libcrc32c virtio_net net_failover serio_raw failover ata_generic virtio_blk pata_acpi floppy
[40595.863155] CR2: 0000000000000108
[40595.863551] ---[ end trace 22209bbcacb4addd ]---
v4: Julian Anastasov remind skb->dev also could be NULL in icmp_send. We'd
better still use dst.dev and do a check to avoid crash.
v3: only replace pkg to packets in cover letter. So I didn't update the version
info in the follow up patches.
v2: fix it in __icmp_send() and decode_session{4,6} separately instead of
updating shared dst dev in {ip_md, ip6}_tunnel_xmit.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
anthraxx
referenced
this issue
in anthraxx/linux-hardened
Oct 1, 2019
[ Upstream commit 769a807 ] syzbot reported a splat: xfrm_policy_inexact_list_reinsert+0x625/0x6e0 net/xfrm/xfrm_policy.c:877 CPU: 1 PID: 6756 Comm: syz-executor.1 Not tainted 5.3.0-rc2+ #57 Call Trace: xfrm_policy_inexact_node_reinsert net/xfrm/xfrm_policy.c:922 [inline] xfrm_policy_inexact_node_merge net/xfrm/xfrm_policy.c:958 [inline] xfrm_policy_inexact_insert_node+0x537/0xb50 net/xfrm/xfrm_policy.c:1023 xfrm_policy_inexact_alloc_chain+0x62b/0xbd0 net/xfrm/xfrm_policy.c:1139 xfrm_policy_inexact_insert+0xe8/0x1540 net/xfrm/xfrm_policy.c:1182 xfrm_policy_insert+0xdf/0xce0 net/xfrm/xfrm_policy.c:1574 xfrm_add_policy+0x4cf/0x9b0 net/xfrm/xfrm_user.c:1670 xfrm_user_rcv_msg+0x46b/0x720 net/xfrm/xfrm_user.c:2676 netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2477 xfrm_netlink_rcv+0x74/0x90 net/xfrm/xfrm_user.c:2684 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] netlink_unicast+0x809/0x9a0 net/netlink/af_netlink.c:1328 netlink_sendmsg+0xa70/0xd30 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:637 [inline] sock_sendmsg net/socket.c:657 [inline] There is no reproducer, however, the warning can be reproduced by adding rules with ever smaller prefixes. The sanity check ("does the policy match the node") uses the prefix value of the node before its updated to the smaller value. To fix this, update the prefix earlier. The bug has no impact on tree correctness, this is only to prevent a false warning. Reported-by: syzbot+8cc27ace5f6972910b31@syzkaller.appspotmail.com Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
anthraxx
referenced
this issue
in anthraxx/linux-hardened
May 7, 2020
Here's the KASAN report: BUG: KASAN: use-after-free in skcipher_crypt_done+0xe8/0x1a8 Read of size 1 at addr ffff00002304001c by task swapper/0/0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc1-00162-gfcb90d5 #57 Hardware name: LS1046A RDB Board (DT) Call trace: dump_backtrace+0x0/0x260 show_stack+0x14/0x20 dump_stack+0xe8/0x144 print_address_description.isra.11+0x64/0x348 __kasan_report+0x11c/0x230 kasan_report+0xc/0x18 __asan_load1+0x5c/0x68 skcipher_crypt_done+0xe8/0x1a8 caam_jr_dequeue+0x390/0x608 tasklet_action_common.isra.13+0x1ec/0x230 tasklet_action+0x24/0x30 efi_header_end+0x1a4/0x370 irq_exit+0x114/0x128 __handle_domain_irq+0x80/0xe0 gic_handle_irq+0x50/0xa0 el1_irq+0xb8/0x180 _raw_spin_unlock_irq+0x2c/0x78 finish_task_switch+0xa4/0x2f8 __schedule+0x3a4/0x890 schedule_idle+0x28/0x50 do_idle+0x22c/0x338 cpu_startup_entry+0x24/0x40 rest_init+0xf8/0x10c arch_call_rest_init+0xc/0x14 start_kernel+0x774/0x7b4 Allocated by task 263: save_stack+0x24/0xb0 __kasan_kmalloc.isra.10+0xc4/0xe0 kasan_kmalloc+0xc/0x18 __kmalloc+0x178/0x2b8 skcipher_edesc_alloc+0x21c/0x1018 skcipher_encrypt+0x84/0x150 crypto_skcipher_encrypt+0x50/0x68 test_skcipher_vec_cfg+0x4d4/0xc10 test_skcipher_vec+0xf8/0x1d8 alg_test_skcipher+0xec/0x230 alg_test.part.44+0x114/0x4a0 alg_test+0x1c/0x60 cryptomgr_test+0x34/0x58 kthread+0x1b8/0x1c0 ret_from_fork+0x10/0x18 Freed by task 0: save_stack+0x24/0xb0 __kasan_slab_free+0x10c/0x188 kasan_slab_free+0x10/0x18 kfree+0x7c/0x298 skcipher_crypt_done+0xe0/0x1a8 caam_jr_dequeue+0x390/0x608 tasklet_action_common.isra.13+0x1ec/0x230 tasklet_action+0x24/0x30 efi_header_end+0x1a4/0x370 The buggy address belongs to the object at ffff000023040000 which belongs to the cache dma-kmalloc-512 of size 512 The buggy address is located 28 bytes inside of 512-byte region [ffff000023040000, ffff000023040200) The buggy address belongs to the page: page:fffffe00006c1000 refcount:1 mapcount:0 mapping:ffff00093200c400 index:0x0 compound_mapcount: 0 flags: 0xffff00000010200(slab|head) raw: 0ffff00000010200 dead000000000100 dead000000000122 ffff00093200c400 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff00002303ff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff00002303ff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff000023040000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff000023040080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff000023040100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb Fixes: ee38767 ("crypto: caam - support crypto_engine framework for SKCIPHER algorithms") Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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