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Message-ID: <20240506123032.3351895-1-edumazet@google.com>
Date: Mon, 6 May 2024 12:30:32 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>, syzbot <syzkaller@...glegroups.com>,
Jason Xing <kernelxing@...cent.com>, Matthieu Baerts <matttbe@...nel.org>
Subject: [PATCH net-next] mptcp: fix possible NULL dereferences
subflow_add_reset_reason(skb, ...) can fail.
We can not assume mptcp_get_ext(skb) always return a non NULL pointer.
syzbot reported:
general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 0 PID: 5098 Comm: syz-executor132 Not tainted 6.9.0-rc6-syzkaller-01478-gcdc74c9d06e7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:subflow_v6_route_req+0x2c7/0x490 net/mptcp/subflow.c:388
Code: 8d 7b 07 48 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 c0 01 00 00 0f b6 43 07 48 8d 1c c3 48 83 c3 18 48 89 d8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 84 01 00 00 0f b6 5b 01 83 e3 0f 48 89
RSP: 0018:ffffc9000362eb68 EFLAGS: 00010206
RAX: 0000000000000003 RBX: 0000000000000018 RCX: ffff888022039e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88807d961140 R08: ffffffff8b6cb76b R09: 1ffff1100fb2c230
R10: dffffc0000000000 R11: ffffed100fb2c231 R12: dffffc0000000000
R13: ffff888022bfe273 R14: ffff88802cf9cc80 R15: ffff88802ad5a700
FS: 0000555587ad2380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f420c3f9720 CR3: 0000000022bfc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
tcp_conn_request+0xf07/0x32c0 net/ipv4/tcp_input.c:7180
tcp_rcv_state_process+0x183c/0x4500 net/ipv4/tcp_input.c:6663
tcp_v6_do_rcv+0x8b2/0x1310 net/ipv6/tcp_ipv6.c:1673
tcp_v6_rcv+0x22b4/0x30b0 net/ipv6/tcp_ipv6.c:1910
ip6_protocol_deliver_rcu+0xc76/0x1570 net/ipv6/ip6_input.c:438
ip6_input_finish+0x186/0x2d0 net/ipv6/ip6_input.c:483
NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314
NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314
__netif_receive_skb_one_core net/core/dev.c:5625 [inline]
__netif_receive_skb+0x1ea/0x650 net/core/dev.c:5739
netif_receive_skb_internal net/core/dev.c:5825 [inline]
netif_receive_skb+0x1e8/0x890 net/core/dev.c:5885
tun_rx_batched+0x1b7/0x8f0 drivers/net/tun.c:1549
tun_get_user+0x2f35/0x4560 drivers/net/tun.c:2002
tun_chr_write_iter+0x113/0x1f0 drivers/net/tun.c:2048
call_write_iter include/linux/fs.h:2110 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xa84/0xcb0 fs/read_write.c:590
ksys_write+0x1a0/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Fixes: 3e140491dd80 ("mptcp: support rstreason for passive reset")
Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jason Xing <kernelxing@...cent.com>
Cc: Matthieu Baerts (NGI0) <matttbe@...nel.org>
Cc: Paolo Abeni <pabeni@...hat.com>
---
net/mptcp/subflow.c | 32 +++++++++++++++++---------------
1 file changed, 17 insertions(+), 15 deletions(-)
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 97ec44d1df308f53e8ebabe6f77c8c86859b5a36..7208d824be353476496271e971ccafde1a47b959 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -287,6 +287,16 @@ int mptcp_subflow_init_cookie_req(struct request_sock *req,
}
EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
+static enum sk_rst_reason mptcp_get_rst_reason(const struct sk_buff *skb)
+{
+ const struct mptcp_ext *mpext = mptcp_get_ext(skb);
+
+ if (!mpext)
+ return SK_RST_REASON_NOT_SPECIFIED;
+
+ return sk_rst_convert_mptcp_reason(mpext->reset_reason);
+}
+
static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
@@ -308,13 +318,9 @@ static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
return dst;
dst_release(dst);
- if (!req->syncookie) {
- struct mptcp_ext *mpext = mptcp_get_ext(skb);
- enum sk_rst_reason reason;
-
- reason = sk_rst_convert_mptcp_reason(mpext->reset_reason);
- tcp_request_sock_ops.send_reset(sk, skb, reason);
- }
+ if (!req->syncookie)
+ tcp_request_sock_ops.send_reset(sk, skb,
+ mptcp_get_rst_reason(skb));
return NULL;
}
@@ -381,13 +387,9 @@ static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
return dst;
dst_release(dst);
- if (!req->syncookie) {
- struct mptcp_ext *mpext = mptcp_get_ext(skb);
- enum sk_rst_reason reason;
-
- reason = sk_rst_convert_mptcp_reason(mpext->reset_reason);
- tcp6_request_sock_ops.send_reset(sk, skb, reason);
- }
+ if (!req->syncookie)
+ tcp6_request_sock_ops.send_reset(sk, skb,
+ mptcp_get_rst_reason(skb));
return NULL;
}
#endif
@@ -923,7 +925,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
tcp_rsk(req)->drop_req = true;
inet_csk_prepare_for_destroy_sock(child);
tcp_done(child);
- reason = sk_rst_convert_mptcp_reason(mptcp_get_ext(skb)->reset_reason);
+ reason = mptcp_get_rst_reason(skb);
req->rsk_ops->send_reset(sk, skb, reason);
/* The last child reference will be released by the caller */
--
2.45.0.rc1.225.g2a3ae87e7f-goog
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