4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mathieu Xhonneux m.xhonneux@gmail.com
[ Upstream commit bbb40a0b75209734ff9286f3326171638c9f6569 ]
seg6_do_srh_encap and seg6_do_srh_inline can possibly do an out-of-bounds access when adding the SRH to the packet. This no longer happen when expanding the skb not only by the size of the SRH (+ outer IPv6 header), but also by skb->mac_len.
[ 53.793056] BUG: KASAN: use-after-free in seg6_do_srh_encap+0x284/0x620 [ 53.794564] Write of size 14 at addr ffff88011975ecfa by task ping/674
[ 53.796665] CPU: 0 PID: 674 Comm: ping Not tainted 4.17.0-rc3-ARCH+ #90 [ 53.796670] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014 [ 53.796673] Call Trace: [ 53.796679] <IRQ> [ 53.796689] dump_stack+0x71/0xab [ 53.796700] print_address_description+0x6a/0x270 [ 53.796707] kasan_report+0x258/0x380 [ 53.796715] ? seg6_do_srh_encap+0x284/0x620 [ 53.796722] memmove+0x34/0x50 [ 53.796730] seg6_do_srh_encap+0x284/0x620 [ 53.796741] ? seg6_do_srh+0x29b/0x360 [ 53.796747] seg6_do_srh+0x29b/0x360 [ 53.796756] seg6_input+0x2e/0x2e0 [ 53.796765] lwtunnel_input+0x93/0xd0 [ 53.796774] ipv6_rcv+0x690/0x920 [ 53.796783] ? ip6_input+0x170/0x170 [ 53.796791] ? eth_gro_receive+0x2d0/0x2d0 [ 53.796800] ? ip6_input+0x170/0x170 [ 53.796809] __netif_receive_skb_core+0xcc0/0x13f0 [ 53.796820] ? netdev_info+0x110/0x110 [ 53.796827] ? napi_complete_done+0xb6/0x170 [ 53.796834] ? e1000_clean+0x6da/0xf70 [ 53.796845] ? process_backlog+0x129/0x2a0 [ 53.796853] process_backlog+0x129/0x2a0 [ 53.796862] net_rx_action+0x211/0x5c0 [ 53.796870] ? napi_complete_done+0x170/0x170 [ 53.796887] ? run_rebalance_domains+0x11f/0x150 [ 53.796891] __do_softirq+0x10e/0x39e [ 53.796894] do_softirq_own_stack+0x2a/0x40 [ 53.796895] </IRQ> [ 53.796898] do_softirq.part.16+0x54/0x60 [ 53.796900] __local_bh_enable_ip+0x5b/0x60 [ 53.796903] ip6_finish_output2+0x416/0x9f0 [ 53.796906] ? ip6_dst_lookup_flow+0x110/0x110 [ 53.796909] ? ip6_sk_dst_lookup_flow+0x390/0x390 [ 53.796911] ? __rcu_read_unlock+0x66/0x80 [ 53.796913] ? ip6_mtu+0x44/0xf0 [ 53.796916] ? ip6_output+0xfc/0x220 [ 53.796918] ip6_output+0xfc/0x220 [ 53.796921] ? ip6_finish_output+0x2b0/0x2b0 [ 53.796923] ? memcpy+0x34/0x50 [ 53.796926] ip6_send_skb+0x43/0xc0 [ 53.796929] rawv6_sendmsg+0x1216/0x1530 [ 53.796932] ? __orc_find+0x6b/0xc0 [ 53.796934] ? rawv6_rcv_skb+0x160/0x160 [ 53.796937] ? __rcu_read_unlock+0x66/0x80 [ 53.796939] ? __rcu_read_unlock+0x66/0x80 [ 53.796942] ? is_bpf_text_address+0x1e/0x30 [ 53.796944] ? kernel_text_address+0xec/0x100 [ 53.796946] ? __kernel_text_address+0xe/0x30 [ 53.796948] ? unwind_get_return_address+0x2f/0x50 [ 53.796950] ? __save_stack_trace+0x92/0x100 [ 53.796954] ? save_stack+0x89/0xb0 [ 53.796956] ? kasan_kmalloc+0xa0/0xd0 [ 53.796958] ? kmem_cache_alloc+0xd2/0x1f0 [ 53.796961] ? prepare_creds+0x23/0x160 [ 53.796963] ? __x64_sys_capset+0x252/0x3e0 [ 53.796966] ? do_syscall_64+0x69/0x160 [ 53.796968] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 53.796971] ? __alloc_pages_nodemask+0x170/0x380 [ 53.796973] ? __alloc_pages_slowpath+0x12c0/0x12c0 [ 53.796977] ? tty_vhangup+0x20/0x20 [ 53.796979] ? policy_nodemask+0x1a/0x90 [ 53.796982] ? __mod_node_page_state+0x8d/0xa0 [ 53.796986] ? __check_object_size+0xe7/0x240 [ 53.796989] ? __sys_sendto+0x229/0x290 [ 53.796991] ? rawv6_rcv_skb+0x160/0x160 [ 53.796993] __sys_sendto+0x229/0x290 [ 53.796996] ? __ia32_sys_getpeername+0x50/0x50 [ 53.796999] ? commit_creds+0x2de/0x520 [ 53.797002] ? security_capset+0x57/0x70 [ 53.797004] ? __x64_sys_capset+0x29f/0x3e0 [ 53.797007] ? __x64_sys_rt_sigsuspend+0xe0/0xe0 [ 53.797011] ? __do_page_fault+0x664/0x770 [ 53.797014] __x64_sys_sendto+0x74/0x90 [ 53.797017] do_syscall_64+0x69/0x160 [ 53.797019] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 53.797022] RIP: 0033:0x7f43b7a6714a [ 53.797023] RSP: 002b:00007ffd891bd368 EFLAGS: 00000246 ORIG_RAX: 000000000000002c [ 53.797026] RAX: ffffffffffffffda RBX: 00000000006129c0 RCX: 00007f43b7a6714a [ 53.797028] RDX: 0000000000000040 RSI: 00000000006129c0 RDI: 0000000000000004 [ 53.797029] RBP: 00007ffd891be640 R08: 0000000000610940 R09: 000000000000001c [ 53.797030] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000040 [ 53.797032] R13: 000000000060e6a0 R14: 0000000000008004 R15: 000000000040b661
[ 53.797171] Allocated by task 642: [ 53.797460] kasan_kmalloc+0xa0/0xd0 [ 53.797463] kmem_cache_alloc+0xd2/0x1f0 [ 53.797465] getname_flags+0x40/0x210 [ 53.797467] user_path_at_empty+0x1d/0x40 [ 53.797469] do_faccessat+0x12a/0x320 [ 53.797471] do_syscall_64+0x69/0x160 [ 53.797473] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 53.797607] Freed by task 642: [ 53.797869] __kasan_slab_free+0x130/0x180 [ 53.797871] kmem_cache_free+0xa8/0x230 [ 53.797872] filename_lookup+0x15b/0x230 [ 53.797874] do_faccessat+0x12a/0x320 [ 53.797876] do_syscall_64+0x69/0x160 [ 53.797878] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 53.798014] The buggy address belongs to the object at ffff88011975e600 which belongs to the cache names_cache of size 4096 [ 53.799043] The buggy address is located 1786 bytes inside of 4096-byte region [ffff88011975e600, ffff88011975f600) [ 53.800013] The buggy address belongs to the page: [ 53.800414] page:ffffea000465d600 count:1 mapcount:0 mapping:0000000000000000 index:0x0 compound_mapcount: 0 [ 53.801259] flags: 0x17fff0000008100(slab|head) [ 53.801640] raw: 017fff0000008100 0000000000000000 0000000000000000 0000000100070007 [ 53.803147] raw: dead000000000100 dead000000000200 ffff88011b185a40 0000000000000000 [ 53.803787] page dumped because: kasan: bad access detected
[ 53.804384] Memory state around the buggy address: [ 53.804788] ffff88011975eb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 53.805384] ffff88011975ec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 53.805979] >ffff88011975ec80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 53.806577] ^ [ 53.807165] ffff88011975ed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 53.807762] ffff88011975ed80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 53.808356] ================================================================== [ 53.808949] Disabling lock debugging due to kernel taint
Fixes: 6c8702c60b88 ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels") Signed-off-by: David Lebrun dlebrun@google.com Signed-off-by: Mathieu Xhonneux m.xhonneux@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/seg6_iptunnel.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -103,7 +103,7 @@ int seg6_do_srh_encap(struct sk_buff *sk hdrlen = (osrh->hdrlen + 1) << 3; tot_len = hdrlen + sizeof(*hdr);
- err = skb_cow_head(skb, tot_len); + err = skb_cow_head(skb, tot_len + skb->mac_len); if (unlikely(err)) return err;
@@ -161,7 +161,7 @@ int seg6_do_srh_inline(struct sk_buff *s
hdrlen = (osrh->hdrlen + 1) << 3;
- err = skb_cow_head(skb, hdrlen); + err = skb_cow_head(skb, hdrlen + skb->mac_len); if (unlikely(err)) return err;