From: Eric Dumazet edumazet@google.com
[ Upstream commit 20ff83f10f113c88d0bb74589389b05250994c16 ]
Before calling __ip_options_compile(), we need to ensure the network header is a an IPv4 one, and that it is already pulled in skb->head.
RAW sockets going through a tunnel can end up calling ipv4_link_failure() with total garbage in the skb, or arbitrary lengthes.
syzbot report :
BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:355 [inline] BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0x294/0x1120 net/ipv4/ip_options.c:123 Write of size 69 at addr ffff888096abf068 by task syz-executor.4/9204
CPU: 0 PID: 9204 Comm: syz-executor.4 Not tainted 5.1.0-rc5+ #77 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x123/0x190 mm/kasan/generic.c:191 memcpy+0x38/0x50 mm/kasan/common.c:133 memcpy include/linux/string.h:355 [inline] __ip_options_echo+0x294/0x1120 net/ipv4/ip_options.c:123 __icmp_send+0x725/0x1400 net/ipv4/icmp.c:695 ipv4_link_failure+0x29f/0x550 net/ipv4/route.c:1204 dst_link_failure include/net/dst.h:427 [inline] vti6_xmit net/ipv6/ip6_vti.c:514 [inline] vti6_tnl_xmit+0x10d4/0x1c0c net/ipv6/ip6_vti.c:553 __netdev_start_xmit include/linux/netdevice.h:4414 [inline] netdev_start_xmit include/linux/netdevice.h:4423 [inline] xmit_one net/core/dev.c:3292 [inline] dev_hard_start_xmit+0x1b2/0x980 net/core/dev.c:3308 __dev_queue_xmit+0x271d/0x3060 net/core/dev.c:3878 dev_queue_xmit+0x18/0x20 net/core/dev.c:3911 neigh_direct_output+0x16/0x20 net/core/neighbour.c:1527 neigh_output include/net/neighbour.h:508 [inline] ip_finish_output2+0x949/0x1740 net/ipv4/ip_output.c:229 ip_finish_output+0x73c/0xd50 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip_output+0x21f/0x670 net/ipv4/ip_output.c:405 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:289 [inline] raw_send_hdrinc net/ipv4/raw.c:432 [inline] raw_sendmsg+0x1d2b/0x2f20 net/ipv4/raw.c:663 inet_sendmsg+0x147/0x5d0 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xdd/0x130 net/socket.c:661 sock_write_iter+0x27c/0x3e0 net/socket.c:988 call_write_iter include/linux/fs.h:1866 [inline] new_sync_write+0x4c7/0x760 fs/read_write.c:474 __vfs_write+0xe4/0x110 fs/read_write.c:487 vfs_write+0x20c/0x580 fs/read_write.c:549 ksys_write+0x14f/0x2d0 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:608 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458c29 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f293b44bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458c29 RDX: 0000000000000014 RSI: 00000000200002c0 RDI: 0000000000000003 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f293b44c6d4 R13: 00000000004c8623 R14: 00000000004ded68 R15: 00000000ffffffff
The buggy address belongs to the page: page:ffffea00025aafc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x1fffc0000000000() raw: 01fffc0000000000 0000000000000000 ffffffff025a0101 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff888096abef80: 00 00 00 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 f2 ffff888096abf000: f2 f2 f2 f2 00 00 00 00 00 00 00 00 00 00 00 00
ffff888096abf080: 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00
^ ffff888096abf100: 00 00 00 00 f1 f1 f1 f1 00 00 f3 f3 00 00 00 00 ffff888096abf180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Fixes: ed0de45a1008 ("ipv4: recompile ip options in ipv4_link_failure") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Stephen Suryaputra ssuryaextr@gmail.com Acked-by: Willem de Bruijn willemb@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/route.c | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-)
--- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1192,25 +1192,39 @@ static struct dst_entry *ipv4_dst_check( return dst; }
-static void ipv4_link_failure(struct sk_buff *skb) +static void ipv4_send_dest_unreach(struct sk_buff *skb) { struct ip_options opt; - struct rtable *rt; int res;
/* Recompile ip options since IPCB may not be valid anymore. + * Also check we have a reasonable ipv4 header. */ - memset(&opt, 0, sizeof(opt)); - opt.optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr); - - rcu_read_lock(); - res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL); - rcu_read_unlock(); - - if (res) + if (!pskb_network_may_pull(skb, sizeof(struct iphdr)) || + ip_hdr(skb)->version != 4 || ip_hdr(skb)->ihl < 5) return;
+ memset(&opt, 0, sizeof(opt)); + if (ip_hdr(skb)->ihl > 5) { + if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4)) + return; + opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr); + + rcu_read_lock(); + res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL); + rcu_read_unlock(); + + if (res) + return; + } __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &opt); +} + +static void ipv4_link_failure(struct sk_buff *skb) +{ + struct rtable *rt; + + ipv4_send_dest_unreach(skb);
rt = skb_rtable(skb); if (rt)