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authorKuniyuki Iwashima <kuniyu@amazon.com>2024-03-15 15:47:10 -0700
committerJakub Kicinski <kuba@kernel.org>2024-03-19 19:35:59 -0700
commit956c0d6191075f0592367512bf07aede458f0151 (patch)
tree3c27f57f732e6d4ce846b1f802098350a2a0441c /net
parentd27e2da94a42655861ca4baea30c8cd65546f25d (diff)
tcp: Clear req->syncookie in reqsk_alloc().
syzkaller reported a read of uninit req->syncookie. [0] Originally, req->syncookie was used only in tcp_conn_request() to indicate if we need to encode SYN cookie in SYN+ACK, so the field remains uninitialised in other places. The commit 695751e31a63 ("bpf: tcp: Handle BPF SYN Cookie in cookie_v[46]_check().") added another meaning in ACK path; req->syncookie is set true if SYN cookie is validated by BPF kfunc. After the change, cookie_v[46]_check() always read req->syncookie, but it is not initialised in the normal SYN cookie case as reported by KMSAN. Let's make sure we always initialise req->syncookie in reqsk_alloc(). [0]: BUG: KMSAN: uninit-value in cookie_v4_check+0x22b7/0x29e0 net/ipv4/syncookies.c:477 cookie_v4_check+0x22b7/0x29e0 net/ipv4/syncookies.c:477 tcp_v4_cookie_check net/ipv4/tcp_ipv4.c:1855 [inline] tcp_v4_do_rcv+0xb17/0x10b0 net/ipv4/tcp_ipv4.c:1914 tcp_v4_rcv+0x4ce4/0x5420 net/ipv4/tcp_ipv4.c:2322 ip_protocol_deliver_rcu+0x2a3/0x13d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x332/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_rcv_finish+0x4a2/0x520 net/ipv4/ip_input.c:449 NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0xcd/0x380 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core net/core/dev.c:5538 [inline] __netif_receive_skb+0x319/0x9e0 net/core/dev.c:5652 process_backlog+0x480/0x8b0 net/core/dev.c:5981 __napi_poll+0xe7/0x980 net/core/dev.c:6632 napi_poll net/core/dev.c:6701 [inline] net_rx_action+0x89d/0x1820 net/core/dev.c:6813 __do_softirq+0x1c0/0x7d7 kernel/softirq.c:554 do_softirq+0x9a/0x100 kernel/softirq.c:455 __local_bh_enable_ip+0x9f/0xb0 kernel/softirq.c:382 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:820 [inline] __dev_queue_xmit+0x2776/0x52c0 net/core/dev.c:4362 dev_queue_xmit include/linux/netdevice.h:3091 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0x187a/0x1b70 net/ipv4/ip_output.c:235 __ip_finish_output+0x287/0x810 ip_finish_output+0x4b/0x550 net/ipv4/ip_output.c:323 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x15f/0x3f0 net/ipv4/ip_output.c:433 dst_output include/net/dst.h:450 [inline] ip_local_out net/ipv4/ip_output.c:129 [inline] __ip_queue_xmit+0x1e93/0x2030 net/ipv4/ip_output.c:535 ip_queue_xmit+0x60/0x80 net/ipv4/ip_output.c:549 __tcp_transmit_skb+0x3c70/0x4890 net/ipv4/tcp_output.c:1462 tcp_transmit_skb net/ipv4/tcp_output.c:1480 [inline] tcp_write_xmit+0x3ee1/0x8900 net/ipv4/tcp_output.c:2792 __tcp_push_pending_frames net/ipv4/tcp_output.c:2977 [inline] tcp_send_fin+0xa90/0x12e0 net/ipv4/tcp_output.c:3578 tcp_shutdown+0x198/0x1f0 net/ipv4/tcp.c:2716 inet_shutdown+0x33f/0x5b0 net/ipv4/af_inet.c:923 __sys_shutdown_sock net/socket.c:2425 [inline] __sys_shutdown net/socket.c:2437 [inline] __do_sys_shutdown net/socket.c:2445 [inline] __se_sys_shutdown+0x2a4/0x440 net/socket.c:2443 __x64_sys_shutdown+0x6c/0xa0 net/socket.c:2443 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was stored to memory at: reqsk_alloc include/net/request_sock.h:148 [inline] inet_reqsk_alloc+0x651/0x7a0 net/ipv4/tcp_input.c:6978 cookie_tcp_reqsk_alloc+0xd4/0x900 net/ipv4/syncookies.c:328 cookie_tcp_check net/ipv4/syncookies.c:388 [inline] cookie_v4_check+0x289f/0x29e0 net/ipv4/syncookies.c:420 tcp_v4_cookie_check net/ipv4/tcp_ipv4.c:1855 [inline] tcp_v4_do_rcv+0xb17/0x10b0 net/ipv4/tcp_ipv4.c:1914 tcp_v4_rcv+0x4ce4/0x5420 net/ipv4/tcp_ipv4.c:2322 ip_protocol_deliver_rcu+0x2a3/0x13d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x332/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_rcv_finish+0x4a2/0x520 net/ipv4/ip_input.c:449 NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0xcd/0x380 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core net/core/dev.c:5538 [inline] __netif_receive_skb+0x319/0x9e0 net/core/dev.c:5652 process_backlog+0x480/0x8b0 net/core/dev.c:5981 __napi_poll+0xe7/0x980 net/core/dev.c:6632 napi_poll net/core/dev.c:6701 [inline] net_rx_action+0x89d/0x1820 net/core/dev.c:6813 __do_softirq+0x1c0/0x7d7 kernel/softirq.c:554 Uninit was created at: __alloc_pages+0x9a7/0xe00 mm/page_alloc.c:4592 __alloc_pages_node include/linux/gfp.h:238 [inline] alloc_pages_node include/linux/gfp.h:261 [inline] alloc_slab_page mm/slub.c:2175 [inline] allocate_slab mm/slub.c:2338 [inline] new_slab+0x2de/0x1400 mm/slub.c:2391 ___slab_alloc+0x1184/0x33d0 mm/slub.c:3525 __slab_alloc mm/slub.c:3610 [inline] __slab_alloc_node mm/slub.c:3663 [inline] slab_alloc_node mm/slub.c:3835 [inline] kmem_cache_alloc+0x6d3/0xbe0 mm/slub.c:3852 reqsk_alloc include/net/request_sock.h:131 [inline] inet_reqsk_alloc+0x66/0x7a0 net/ipv4/tcp_input.c:6978 tcp_conn_request+0x484/0x44e0 net/ipv4/tcp_input.c:7135 tcp_v4_conn_request+0x16f/0x1d0 net/ipv4/tcp_ipv4.c:1716 tcp_rcv_state_process+0x2e5/0x4bb0 net/ipv4/tcp_input.c:6655 tcp_v4_do_rcv+0xbfd/0x10b0 net/ipv4/tcp_ipv4.c:1929 tcp_v4_rcv+0x4ce4/0x5420 net/ipv4/tcp_ipv4.c:2322 ip_protocol_deliver_rcu+0x2a3/0x13d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x332/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_sublist_rcv_finish net/ipv4/ip_input.c:580 [inline] ip_list_rcv_finish net/ipv4/ip_input.c:631 [inline] ip_sublist_rcv+0x15f3/0x17f0 net/ipv4/ip_input.c:639 ip_list_rcv+0x9ef/0xa40 net/ipv4/ip_input.c:674 __netif_receive_skb_list_ptype net/core/dev.c:5581 [inline] __netif_receive_skb_list_core+0x15c5/0x1670 net/core/dev.c:5629 __netif_receive_skb_list net/core/dev.c:5681 [inline] netif_receive_skb_list_internal+0x106c/0x16f0 net/core/dev.c:5773 gro_normal_list include/net/gro.h:438 [inline] napi_complete_done+0x425/0x880 net/core/dev.c:6113 virtqueue_napi_complete drivers/net/virtio_net.c:465 [inline] virtnet_poll+0x149d/0x2240 drivers/net/virtio_net.c:2211 __napi_poll+0xe7/0x980 net/core/dev.c:6632 napi_poll net/core/dev.c:6701 [inline] net_rx_action+0x89d/0x1820 net/core/dev.c:6813 __do_softirq+0x1c0/0x7d7 kernel/softirq.c:554 CPU: 0 PID: 16792 Comm: syz-executor.2 Not tainted 6.8.0-syzkaller-05562-g61387b8dcf1d #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Fixes: 695751e31a63 ("bpf: tcp: Handle BPF SYN Cookie in cookie_v[46]_check().") Reported-by: syzkaller <syzkaller@googlegroups.com> Reported-by: Eric Dumazet <edumazet@google.com> Closes: https://lore.kernel.org/bpf/CANn89iKdN9c+C_2JAUbc+VY3DDQjAQukMtiBbormAmAk9CdvQA@mail.gmail.com/ Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20240315224710.55209-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/syncookies.c3
-rw-r--r--net/ipv6/syncookies.c3
2 files changed, 6 insertions, 0 deletions
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 7972ad3d7c73..500f665f98cb 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -474,6 +474,9 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
ireq->wscale_ok, &rcv_wscale,
dst_metric(&rt->dst, RTAX_INITRWND));
+ /* req->syncookie is set true only if ACK is validated
+ * by BPF kfunc, then, rcv_wscale is already configured.
+ */
if (!req->syncookie)
ireq->rcv_wscale = rcv_wscale;
ireq->ecn_ok &= cookie_ecn_ok(net, &rt->dst);
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 8bad0a44a0a6..6d8286c299c9 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -258,6 +258,9 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
ireq->wscale_ok, &rcv_wscale,
dst_metric(dst, RTAX_INITRWND));
+ /* req->syncookie is set true only if ACK is validated
+ * by BPF kfunc, then, rcv_wscale is already configured.
+ */
if (!req->syncookie)
ireq->rcv_wscale = rcv_wscale;
ireq->ecn_ok &= cookie_ecn_ok(net, dst);