From 02f0717e9835dbdeee26084e42086fbd32e64eb8 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 1 Nov 2023 04:52:33 +0000 Subject: [PATCH] net/tcp: fix possible out-of-bounds reads in tcp_hash_fail() syzbot managed to trigger a fault by sending TCP packets with all flags being set. v2: - While fixing this bug, add PSH flag handling and represent flags the way tcpdump does : [S], [S.], [P.] - Print 4-tuples more consistently between families. BUG: KASAN: stack-out-of-bounds in string_nocheck lib/vsprintf.c:645 [inline] BUG: KASAN: stack-out-of-bounds in string+0x394/0x3d0 lib/vsprintf.c:727 Read of size 1 at addr ffffc9000397f3f5 by task syz-executor299/5039 CPU: 1 PID: 5039 Comm: syz-executor299 Not tainted 6.6.0-rc7-syzkaller-02075-g55c900477f5b #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0xc4/0x620 mm/kasan/report.c:475 kasan_report+0xda/0x110 mm/kasan/report.c:588 string_nocheck lib/vsprintf.c:645 [inline] string+0x394/0x3d0 lib/vsprintf.c:727 vsnprintf+0xc5f/0x1870 lib/vsprintf.c:2818 vprintk_store+0x3a0/0xb80 kernel/printk/printk.c:2191 vprintk_emit+0x14c/0x5f0 kernel/printk/printk.c:2288 vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45 _printk+0xc8/0x100 kernel/printk/printk.c:2332 tcp_inbound_hash.constprop.0+0xdb2/0x10d0 include/net/tcp.h:2760 tcp_v6_rcv+0x2b31/0x34d0 net/ipv6/tcp_ipv6.c:1882 ip6_protocol_deliver_rcu+0x33b/0x13d0 net/ipv6/ip6_input.c:438 ip6_input_finish+0x14f/0x2f0 net/ipv6/ip6_input.c:483 NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] ip6_input+0xce/0x440 net/ipv6/ip6_input.c:492 dst_input include/net/dst.h:461 [inline] ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] ipv6_rcv+0x563/0x720 net/ipv6/ip6_input.c:310 __netif_receive_skb_one_core+0x115/0x180 net/core/dev.c:5527 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:5641 netif_receive_skb_internal net/core/dev.c:5727 [inline] netif_receive_skb+0x133/0x700 net/core/dev.c:5786 tun_rx_batched+0x429/0x780 drivers/net/tun.c:1579 tun_get_user+0x29e7/0x3bc0 drivers/net/tun.c:2002 tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:1956 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x650/0xe40 fs/read_write.c:584 ksys_write+0x12f/0x250 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: 2717b5adea9e ("net/tcp: Add tcp_hash_fail() ratelimited logs") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Dmitry Safonov Cc: Francesco Ruggeri Cc: David Ahern Reviewed-by: Dmitry Safonov Signed-off-by: David S. Miller --- include/net/tcp_ao.h | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h index a375a171ef3c..b56be10838f0 100644 --- a/include/net/tcp_ao.h +++ b/include/net/tcp_ao.h @@ -124,7 +124,7 @@ struct tcp_ao_info { #define tcp_hash_fail(msg, family, skb, fmt, ...) \ do { \ const struct tcphdr *th = tcp_hdr(skb); \ - char hdr_flags[5] = {}; \ + char hdr_flags[6]; \ char *f = hdr_flags; \ \ if (th->fin) \ @@ -133,17 +133,18 @@ do { \ *f++ = 'S'; \ if (th->rst) \ *f++ = 'R'; \ + if (th->psh) \ + *f++ = 'P'; \ if (th->ack) \ - *f++ = 'A'; \ - if (f != hdr_flags) \ - *f = ' '; \ + *f++ = '.'; \ + *f = 0; \ if ((family) == AF_INET) { \ - net_info_ratelimited("%s for (%pI4, %d)->(%pI4, %d) %s" fmt "\n", \ + net_info_ratelimited("%s for %pI4.%d->%pI4.%d [%s] " fmt "\n", \ msg, &ip_hdr(skb)->saddr, ntohs(th->source), \ &ip_hdr(skb)->daddr, ntohs(th->dest), \ hdr_flags, ##__VA_ARGS__); \ } else { \ - net_info_ratelimited("%s for [%pI6c]:%u->[%pI6c]:%u %s" fmt "\n", \ + net_info_ratelimited("%s for [%pI6c].%d->[%pI6c].%d [%s]" fmt "\n", \ msg, &ipv6_hdr(skb)->saddr, ntohs(th->source), \ &ipv6_hdr(skb)->daddr, ntohs(th->dest), \ hdr_flags, ##__VA_ARGS__); \ -- 2.34.1