6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kuniyuki Iwashima kuniyu@amazon.com
commit 8702cf12e6ba91616a72d684e90357977972991b upstream.
syzbot reported a warning [0] introduced by commit c48ef9c4aed3 ("tcp: Fix bind() regression for v4-mapped-v6 non-wildcard address.").
After the cited commit, a v4 socket's address matches the corresponding v4-mapped-v6 tb2 in inet_bind2_bucket_match_addr(), not vice versa.
During X.X.X.X -> ::ffff:X.X.X.X order bind()s, the second bind() uses bhash and conflicts properly without checking bhash2 so that we need not check if a v4-mapped-v6 sk matches the corresponding v4 address tb2 in inet_bind2_bucket_match_addr(). However, the repro shows that we need to check that in a no-conflict case.
The repro bind()s two sockets to the 2-tuples using SO_REUSEPORT and calls listen() for the first socket:
from socket import *
s1 = socket() s1.setsockopt(SOL_SOCKET, SO_REUSEPORT, 1) s1.bind(('127.0.0.1', 0))
s2 = socket(AF_INET6) s2.setsockopt(SOL_SOCKET, SO_REUSEPORT, 1) s2.bind(('::ffff:127.0.0.1', s1.getsockname()[1]))
s1.listen()
The second socket should belong to the first socket's tb2, but the second bind() creates another tb2 bucket because inet_bind2_bucket_find() returns NULL in inet_csk_get_port() as the v4-mapped-v6 sk does not match the corresponding v4 address tb2.
bhash2[] -> tb2(::ffff:X.X.X.X) -> tb2(X.X.X.X)
Then, listen() for the first socket calls inet_csk_get_port(), where the v4 address matches the v4-mapped-v6 tb2 and WARN_ON() is triggered.
To avoid that, we need to check if v4-mapped-v6 sk address matches with the corresponding v4 address tb2 in inet_bind2_bucket_match().
The same checks are needed in inet_bind2_bucket_addr_match() too, so we can move all checks there and call it from inet_bind2_bucket_match().
Note that now tb->family is just an address family of tb->(v6_)?rcv_saddr and not of sockets in the bucket. This could be refactored later by defining tb->rcv_saddr as tb->v6_rcv_saddr.s6_addr32[3] and prepending ::ffff: when creating v4 tb2.
[0]: WARNING: CPU: 0 PID: 5049 at net/ipv4/inet_connection_sock.c:587 inet_csk_get_port+0xf96/0x2350 net/ipv4/inet_connection_sock.c:587 Modules linked in: CPU: 0 PID: 5049 Comm: syz-executor288 Not tainted 6.6.0-rc2-syzkaller-00018-g2cf0f7156238 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023 RIP: 0010:inet_csk_get_port+0xf96/0x2350 net/ipv4/inet_connection_sock.c:587 Code: 7c 24 08 e8 4c b6 8a 01 31 d2 be 88 01 00 00 48 c7 c7 e0 94 ae 8b e8 59 2e a3 f8 2e 2e 2e 31 c0 e9 04 fe ff ff e8 ca 88 d0 f8 <0f> 0b e9 0f f9 ff ff e8 be 88 d0 f8 49 8d 7e 48 e8 65 ca 5a 00 31 RSP: 0018:ffffc90003abfbf0 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff888026429100 RCX: 0000000000000000 RDX: ffff88807edcbb80 RSI: ffffffff88b73d66 RDI: ffff888026c49f38 RBP: ffff888026c49f30 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff9260f200 R13: ffff888026c49880 R14: 0000000000000000 R15: ffff888026429100 FS: 00005555557d5380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000045ad50 CR3: 0000000025754000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> inet_csk_listen_start+0x155/0x360 net/ipv4/inet_connection_sock.c:1256 __inet_listen_sk+0x1b8/0x5c0 net/ipv4/af_inet.c:217 inet_listen+0x93/0xd0 net/ipv4/af_inet.c:239 __sys_listen+0x194/0x270 net/socket.c:1866 __do_sys_listen net/socket.c:1875 [inline] __se_sys_listen net/socket.c:1873 [inline] __x64_sys_listen+0x53/0x80 net/socket.c:1873 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 RIP: 0033:0x7f3a5bce3af9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc1a1c79e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000032 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3a5bce3af9 RDX: 00007f3a5bce3af9 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f3a5bd565f0 R08: 0000000000000006 R09: 0000000000000006 R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000001 R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001 </TASK>
Fixes: c48ef9c4aed3 ("tcp: Fix bind() regression for v4-mapped-v6 non-wildcard address.") Reported-by: syzbot+71e724675ba3958edb31@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=71e724675ba3958edb31 Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Reviewed-by: Eric Dumazet edumazet@google.com Link: https://lore.kernel.org/r/20231010013814.70571-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/inet_hashtables.c | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-)
--- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -148,8 +148,14 @@ static bool inet_bind2_bucket_addr_match const struct sock *sk) { #if IS_ENABLED(CONFIG_IPV6) - if (sk->sk_family != tb2->family) - return false; + if (sk->sk_family != tb2->family) { + if (sk->sk_family == AF_INET) + return ipv6_addr_v4mapped(&tb2->v6_rcv_saddr) && + tb2->v6_rcv_saddr.s6_addr32[3] == sk->sk_rcv_saddr; + + return ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr) && + sk->sk_v6_rcv_saddr.s6_addr32[3] == tb2->rcv_saddr; + }
if (sk->sk_family == AF_INET6) return ipv6_addr_equal(&tb2->v6_rcv_saddr, @@ -799,19 +805,7 @@ static bool inet_bind2_bucket_match(cons tb->l3mdev != l3mdev) return false;
-#if IS_ENABLED(CONFIG_IPV6) - if (sk->sk_family != tb->family) { - if (sk->sk_family == AF_INET) - return ipv6_addr_v4mapped(&tb->v6_rcv_saddr) && - tb->v6_rcv_saddr.s6_addr32[3] == sk->sk_rcv_saddr; - - return false; - } - - if (sk->sk_family == AF_INET6) - return ipv6_addr_equal(&tb->v6_rcv_saddr, &sk->sk_v6_rcv_saddr); -#endif - return tb->rcv_saddr == sk->sk_rcv_saddr; + return inet_bind2_bucket_addr_match(tb, sk); }
bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const struct net *net,