[PATCH net] ipv6: tcp: fix flowlabels reflection for RST packets

[PATCH net] ipv6: tcp: fix flowlabels reflection for RST packets

[Eric Dumazet]

In 323a53c41292 ("ipv6: tcp: enable flowlabel reflection in some RST packets")
and 50a8accf1062 ("ipv6: tcp: send consistent flowlabel in TIME_WAIT state")
we took care of IPv6 flowlabel reflections for two cases.

This patch takes care of the remaining case, when the RST packet
is sent on behalf of a 'full' socket.

In Marek use case, this was a socket in TCP_CLOSE state.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Marek Majkowski <marek@cloudflare.com>
Tested-by: Marek Majkowski <marek@cloudflare.com>
---
 net/ipv6/tcp_ipv6.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d56a9019a0feb5a34312ec353c555f44b8c09b3d..5da069e91cacca4e84a3e41dae4746c9d38fcc46 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -984,8 +984,13 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
 
 	if (sk) {
 		oif = sk->sk_bound_dev_if;
-		if (sk_fullsock(sk))
+		if (sk_fullsock(sk)) {
+			const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+
 			trace_tcp_send_reset(sk, skb);
+			if (np->repflow)
+				label = ip6_flowlabel(ipv6h);
+		}
 		if (sk->sk_state == TCP_TIME_WAIT)
 			label = cpu_to_be32(inet_twsk(sk)->tw_flowlabel);
 	} else {
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH net] ipv6: fix potential crash in ip6_datagram_dst_update()

[Eric Dumazet]

Willem forgot to change one of the calls to fl6_sock_lookup(),
which can now return an error or NULL.

syzbot reported :

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 31763 Comm: syz-executor.0 Not tainted 5.2.0-rc6+ #63
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ip6_datagram_dst_update+0x559/0xc30 net/ipv6/datagram.c:83
Code: 00 00 e8 ea 29 3f fb 4d 85 f6 0f 84 96 04 00 00 e8 dc 29 3f fb 49 8d 7e 20 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 16 06 00 00 4d 8b 6e 20 e8 b4 29 3f fb 4c 89 ee
RSP: 0018:ffff88809ba97ae0 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8880a81254b0 RCX: ffffc90008118000
RDX: 0000000000000003 RSI: ffffffff86319a84 RDI: 000000000000001e
RBP: ffff88809ba97c10 R08: ffff888065e9e700 R09: ffffed1015d26c80
R10: ffffed1015d26c7f R11: ffff8880ae9363fb R12: ffff8880a8124f40
R13: 0000000000000001 R14: fffffffffffffffe R15: ffff88809ba97b40
FS:  00007f38e606a700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000202c0140 CR3: 00000000a026a000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __ip6_datagram_connect+0x5e9/0x1390 net/ipv6/datagram.c:246
 ip6_datagram_connect+0x30/0x50 net/ipv6/datagram.c:269
 ip6_datagram_connect_v6_only+0x69/0x90 net/ipv6/datagram.c:281
 inet_dgram_connect+0x14a/0x2d0 net/ipv4/af_inet.c:571
 __sys_connect+0x264/0x330 net/socket.c:1824
 __do_sys_connect net/socket.c:1835 [inline]
 __se_sys_connect net/socket.c:1832 [inline]
 __x64_sys_connect+0x73/0xb0 net/socket.c:1832
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4597c9
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f38e6069c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004597c9
RDX: 000000000000001c RSI: 0000000020000040 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f38e606a6d4
R13: 00000000004bfd07 R14: 00000000004d1838 R15: 00000000ffffffff
Modules linked in:
RIP: 0010:ip6_datagram_dst_update+0x559/0xc30 net/ipv6/datagram.c:83
Code: 00 00 e8 ea 29 3f fb 4d 85 f6 0f 84 96 04 00 00 e8 dc 29 3f fb 49 8d 7e 20 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 16 06 00 00 4d 8b 6e 20 e8 b4 29 3f fb 4c 89 ee

Fixes: 59c820b2317f ("ipv6: elide flowlabel check if no exclusive leases exist")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
 net/ipv6/datagram.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 9d78c907b918a98cbb9e80154a038e31b6bddd11..9ab897ded4df52d882cda1414ef0159f3eb1765a 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -74,7 +74,7 @@ int ip6_datagram_dst_update(struct sock *sk, bool fix_sk_saddr)
 
 	if (np->sndflow && (np->flow_label & IPV6_FLOWLABEL_MASK)) {
 		flowlabel = fl6_sock_lookup(sk, np->flow_label);
-		if (!flowlabel)
+		if (IS_ERR(flowlabel))
 			return -EINVAL;
 	}
 	ip6_datagram_flow_key_init(&fl6, sk);
-- 
2.22.0.410.gd8fdbe21b5-goog

Re: [PATCH net] ipv6: fix potential crash in ip6_datagram_dst_update()

[David Miller]

From: Eric Dumazet <edumazet@google.com>
Date: Wed, 10 Jul 2019 06:40:10 -0700

> Willem forgot to change one of the calls to fl6_sock_lookup(),
> which can now return an error or NULL.
> 
> syzbot reported :
 ...
> Fixes: 59c820b2317f ("ipv6: elide flowlabel check if no exclusive leases exist")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Acked-by: Willem de Bruijn <willemb@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>

Applied.

[PATCH net] ipv6: fix static key imbalance in fl_create()

[Eric Dumazet]

fl_create() should call static_branch_deferred_inc() only in
case of success.

Also we should not call fl_free() in error path, as this could
cause a static key imbalance.

jump label: negative count!
WARNING: CPU: 0 PID: 15907 at kernel/jump_label.c:221 static_key_slow_try_dec kernel/jump_label.c:221 [inline]
WARNING: CPU: 0 PID: 15907 at kernel/jump_label.c:221 static_key_slow_try_dec+0x1ab/0x1d0 kernel/jump_label.c:206
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 15907 Comm: syz-executor.2 Not tainted 5.2.0-rc6+ #62
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
 panic+0x2cb/0x744 kernel/panic.c:219
 __warn.cold+0x20/0x4d kernel/panic.c:576
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:986
RIP: 0010:static_key_slow_try_dec kernel/jump_label.c:221 [inline]
RIP: 0010:static_key_slow_try_dec+0x1ab/0x1d0 kernel/jump_label.c:206
Code: c0 e8 e9 3e e5 ff 83 fb 01 0f 85 32 ff ff ff e8 5b 3d e5 ff 45 31 ff eb a0 e8 51 3d e5 ff 48 c7 c7 40 99 92 87 e8 13 75 b7 ff <0f> 0b eb 8b 4c 89 e7 e8 a9 c0 1e 00 e9 de fe ff ff e8 bf 6d b7 ff
RSP: 0018:ffff88805f9c7450 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 00000000ffffffff RCX: 0000000000000000
RDX: 000000000000e3e1 RSI: ffffffff815adb06 RDI: ffffed100bf38e7c
RBP: ffff88805f9c74e0 R08: ffff88806acf0700 R09: ffffed1015d060a9
R10: ffffed1015d060a8 R11: ffff8880ae830547 R12: ffffffff89832ce0
R13: ffff88805f9c74b8 R14: 1ffff1100bf38e8b R15: 00000000ffffff01
 __static_key_slow_dec_deferred+0x65/0x110 kernel/jump_label.c:272
 fl_free+0xa9/0xe0 net/ipv6/ip6_flowlabel.c:121
 fl_create+0x6af/0x9f0 net/ipv6/ip6_flowlabel.c:457
 ipv6_flowlabel_opt+0x80e/0x2730 net/ipv6/ip6_flowlabel.c:624
 do_ipv6_setsockopt.isra.0+0x2119/0x4100 net/ipv6/ipv6_sockglue.c:825
 ipv6_setsockopt+0xf6/0x170 net/ipv6/ipv6_sockglue.c:944
 tcp_setsockopt net/ipv4/tcp.c:3131 [inline]
 tcp_setsockopt+0x8f/0xe0 net/ipv4/tcp.c:3125
 sock_common_setsockopt+0x94/0xd0 net/core/sock.c:3130
 __sys_setsockopt+0x253/0x4b0 net/socket.c:2080
 __do_sys_setsockopt net/socket.c:2096 [inline]
 __se_sys_setsockopt net/socket.c:2093 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2093
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4597c9
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2670556c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00000000004597c9
RDX: 0000000000000020 RSI: 0000000000000029 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 000000000000fdf7 R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000246 R12: 00007f26705576d4
R13: 00000000004cec00 R14: 00000000004dd520 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..

Fixes: 59c820b2317f ("ipv6: elide flowlabel check if no exclusive leases exist")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
 net/ipv6/ip6_flowlabel.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index ad284b1fd308a646f27f715f35d9759fd50c5902..d64b83e856428195c1ecc963a263155c8b4528d0 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -435,8 +435,6 @@ fl_create(struct net *net, struct sock *sk, struct in6_flowlabel_req *freq,
 	}
 	fl->dst = freq->flr_dst;
 	atomic_set(&fl->users, 1);
-	if (fl_shared_exclusive(fl) || fl->opt)
-		static_branch_deferred_inc(&ipv6_flowlabel_exclusive);
 	switch (fl->share) {
 	case IPV6_FL_S_EXCL:
 	case IPV6_FL_S_ANY:
@@ -451,10 +449,15 @@ fl_create(struct net *net, struct sock *sk, struct in6_flowlabel_req *freq,
 		err = -EINVAL;
 		goto done;
 	}
+	if (fl_shared_exclusive(fl) || fl->opt)
+		static_branch_deferred_inc(&ipv6_flowlabel_exclusive);
 	return fl;
 
 done:
-	fl_free(fl);
+	if (fl) {
+		kfree(fl->opt);
+		kfree(fl);
+	}
 	*err_p = err;
 	return NULL;
 }
-- 
2.22.0.410.gd8fdbe21b5-goog

Re: [PATCH net] ipv6: fix static key imbalance in fl_create()

[David Miller]

From: Eric Dumazet <edumazet@google.com>
Date: Wed, 10 Jul 2019 06:40:11 -0700

> fl_create() should call static_branch_deferred_inc() only in
> case of success.
> 
> Also we should not call fl_free() in error path, as this could
> cause a static key imbalance.
 ...
> Fixes: 59c820b2317f ("ipv6: elide flowlabel check if no exclusive leases exist")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Acked-by: Willem de Bruijn <willemb@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>

Applied.

Re: [PATCH net] ipv6: tcp: fix flowlabels reflection for RST packets

[David Miller]

From: Eric Dumazet <edumazet@google.com>
Date: Wed, 10 Jul 2019 06:40:09 -0700

> In 323a53c41292 ("ipv6: tcp: enable flowlabel reflection in some RST packets")
> and 50a8accf1062 ("ipv6: tcp: send consistent flowlabel in TIME_WAIT state")
> we took care of IPv6 flowlabel reflections for two cases.
> 
> This patch takes care of the remaining case, when the RST packet
> is sent on behalf of a 'full' socket.
> 
> In Marek use case, this was a socket in TCP_CLOSE state.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Marek Majkowski <marek@cloudflare.com>
> Tested-by: Marek Majkowski <marek@cloudflare.com>

Applied.