From: Eric Dumazet edumazet@google.com
IP_ECN_decapsulate() and IP6_ECN_decapsulate() assume IP header is already pulled.
geneve does not ensure this yet.
Fixing this generically in IP_ECN_decapsulate() and IP6_ECN_decapsulate() is not possible, since callers pass a pointer that might be freed by pskb_may_pull()
syzbot reported :
BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:238 [inline] BUG: KMSAN: uninit-value in INET_ECN_decapsulate+0x345/0x1db0 include/net/inet_ecn.h:260 CPU: 1 PID: 8941 Comm: syz-executor.0 Not tainted 5.10.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x21c/0x280 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118 __msan_warning+0x5f/0xa0 mm/kmsan/kmsan_instr.c:197 __INET_ECN_decapsulate include/net/inet_ecn.h:238 [inline] INET_ECN_decapsulate+0x345/0x1db0 include/net/inet_ecn.h:260 geneve_rx+0x2103/0x2980 include/net/inet_ecn.h:306 geneve_udp_encap_recv+0x105c/0x1340 drivers/net/geneve.c:377 udp_queue_rcv_one_skb+0x193a/0x1af0 net/ipv4/udp.c:2093 udp_queue_rcv_skb+0x282/0x1050 net/ipv4/udp.c:2167 udp_unicast_rcv_skb net/ipv4/udp.c:2325 [inline] __udp4_lib_rcv+0x399d/0x5880 net/ipv4/udp.c:2394 udp_rcv+0x5c/0x70 net/ipv4/udp.c:2564 ip_protocol_deliver_rcu+0x572/0xc50 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_local_deliver+0x583/0x8d0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:449 [inline] ip_rcv_finish net/ipv4/ip_input.c:428 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_rcv+0x5c3/0x840 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core net/core/dev.c:5315 [inline] __netif_receive_skb+0x1ec/0x640 net/core/dev.c:5429 process_backlog+0x523/0xc10 net/core/dev.c:6319 napi_poll+0x420/0x1010 net/core/dev.c:6763 net_rx_action+0x35c/0xd40 net/core/dev.c:6833 __do_softirq+0x1a9/0x6fa kernel/softirq.c:298 asm_call_irq_on_stack+0xf/0x20 </IRQ> __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0x6e/0x90 arch/x86/kernel/irq_64.c:77 do_softirq kernel/softirq.c:343 [inline] __local_bh_enable_ip+0x184/0x1d0 kernel/softirq.c:195 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32 rcu_read_unlock_bh include/linux/rcupdate.h:730 [inline] __dev_queue_xmit+0x3a9b/0x4520 net/core/dev.c:4167 dev_queue_xmit+0x4b/0x60 net/core/dev.c:4173 packet_snd net/packet/af_packet.c:2992 [inline] packet_sendmsg+0x86f9/0x99d0 net/packet/af_packet.c:3017 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg net/socket.c:671 [inline] __sys_sendto+0x9dc/0xc80 net/socket.c:1992 __do_sys_sendto net/socket.c:2004 [inline] __se_sys_sendto+0x107/0x130 net/socket.c:2000 __x64_sys_sendto+0x6e/0x90 net/socket.c:2000 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 2d07dc79fe04 ("geneve: add initial netdev driver for GENEVE tunnels") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Link: https://lore.kernel.org/r/20201201090507.4137906-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org --- drivers/net/geneve.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c index d89995f4bd433..e6f9fe7fa2a40 100644 --- a/drivers/net/geneve.c +++ b/drivers/net/geneve.c @@ -249,11 +249,21 @@ static void geneve_rx(struct geneve_dev *geneve, struct geneve_sock *gs, skb_dst_set(skb, &tun_dst->dst);
/* Ignore packet loops (and multicast echo) */ - if (ether_addr_equal(eth_hdr(skb)->h_source, geneve->dev->dev_addr)) { - geneve->dev->stats.rx_errors++; - goto drop; + if (ether_addr_equal(eth_hdr(skb)->h_source, geneve->dev->dev_addr)) + goto rx_error; + + switch (skb_protocol(skb, true)) { + case htons(ETH_P_IP): + if (pskb_may_pull(skb, sizeof(struct iphdr))) + goto rx_error; + break; + case htons(ETH_P_IPV6): + if (pskb_may_pull(skb, sizeof(struct ipv6hdr))) + goto rx_error; + break; + default: + goto rx_error; } - oiph = skb_network_header(skb); skb_reset_network_header(skb);
@@ -294,6 +304,8 @@ static void geneve_rx(struct geneve_dev *geneve, struct geneve_sock *gs, u64_stats_update_end(&stats->syncp); } return; +rx_error: + geneve->dev->stats.rx_errors++; drop: /* Consume bad packet */ kfree_skb(skb);