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authorMat Martineau <mathew.j.martineau@linux.intel.com>2021-09-02 21:51:19 +0300
committerDavid S. Miller <davem@davemloft.net>2021-09-03 13:49:30 +0300
commit340fa6667a696338e707cd5531a9631093d1be29 (patch)
tree3089ccee5a2a62cc48a81e5f97c166f002202422 /net
parent20e7b9f82b6e7efc487e2c1a1dededbc4231fe81 (diff)
downloadlinux-340fa6667a696338e707cd5531a9631093d1be29.tar.xz
mptcp: Only send extra TCP acks in eligible socket states
Recent changes exposed a bug where specifically-timed requests to the path manager netlink API could trigger a divide-by-zero in __tcp_select_window(), as syzkaller does: divide error: 0000 [#1] SMP KASAN NOPTI CPU: 0 PID: 9667 Comm: syz-executor.0 Not tainted 5.14.0-rc6+ #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:__tcp_select_window+0x509/0xa60 net/ipv4/tcp_output.c:3016 Code: 44 89 ff e8 c9 29 e9 fd 45 39 e7 0f 8d 20 ff ff ff e8 db 28 e9 fd 44 89 e3 e9 13 ff ff ff e8 ce 28 e9 fd 44 89 e0 44 89 e3 99 <f7> 7c 24 04 29 d3 e9 fc fe ff ff e8 b7 28 e9 fd 44 89 f1 48 89 ea RSP: 0018:ffff888031ccf020 EFLAGS: 00010216 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000040000 RDX: 0000000000000000 RSI: ffff88811532c080 RDI: 0000000000000002 RBP: 0000000000000000 R08: ffffffff835807c2 R09: 0000000000000000 R10: 0000000000000004 R11: ffffed1020b92441 R12: 0000000000000000 R13: 1ffff11006399e08 R14: 0000000000000000 R15: 0000000000000000 FS: 00007fa4c8344700(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2f424000 CR3: 000000003e4e2003 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: tcp_select_window net/ipv4/tcp_output.c:264 [inline] __tcp_transmit_skb+0xc00/0x37a0 net/ipv4/tcp_output.c:1351 __tcp_send_ack.part.0+0x3ec/0x760 net/ipv4/tcp_output.c:3972 __tcp_send_ack net/ipv4/tcp_output.c:3978 [inline] tcp_send_ack+0x7d/0xa0 net/ipv4/tcp_output.c:3978 mptcp_pm_nl_addr_send_ack+0x1ab/0x380 net/mptcp/pm_netlink.c:654 mptcp_pm_remove_addr+0x161/0x200 net/mptcp/pm.c:58 mptcp_nl_remove_id_zero_address+0x197/0x460 net/mptcp/pm_netlink.c:1328 mptcp_nl_cmd_del_addr+0x98b/0xd40 net/mptcp/pm_netlink.c:1359 genl_family_rcv_msg_doit.isra.0+0x225/0x340 net/netlink/genetlink.c:731 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline] genl_rcv_msg+0x341/0x5b0 net/netlink/genetlink.c:792 netlink_rcv_skb+0x148/0x430 net/netlink/af_netlink.c:2504 genl_rcv+0x24/0x40 net/netlink/genetlink.c:803 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x537/0x750 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x846/0xd80 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg+0x14e/0x190 net/socket.c:724 ____sys_sendmsg+0x709/0x870 net/socket.c:2403 ___sys_sendmsg+0xff/0x170 net/socket.c:2457 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2486 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae mptcp_pm_nl_addr_send_ack() was attempting to send a TCP ACK on the first subflow in the MPTCP socket's connection list without validating that the subflow was in a suitable connection state. To address this, always validate subflow state when sending extra ACKs on subflows for address advertisement or subflow priority change. Fixes: 84dfe3677a6f ("mptcp: send out dedicated ADD_ADDR packet") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/229 Co-developed-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Acked-by: Geliang Tang <geliangtang@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/mptcp/pm_netlink.c10
-rw-r--r--net/mptcp/protocol.c21
-rw-r--r--net/mptcp/protocol.h1
3 files changed, 15 insertions, 17 deletions
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 1e4289c507ff..c4f9a5ce3815 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -644,15 +644,12 @@ void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk)
subflow = list_first_entry_or_null(&msk->conn_list, typeof(*subflow), node);
if (subflow) {
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
- bool slow;
spin_unlock_bh(&msk->pm.lock);
pr_debug("send ack for %s",
mptcp_pm_should_add_signal(msk) ? "add_addr" : "rm_addr");
- slow = lock_sock_fast(ssk);
- tcp_send_ack(ssk);
- unlock_sock_fast(ssk, slow);
+ mptcp_subflow_send_ack(ssk);
spin_lock_bh(&msk->pm.lock);
}
}
@@ -669,7 +666,6 @@ int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
struct sock *sk = (struct sock *)msk;
struct mptcp_addr_info local;
- bool slow;
local_address((struct sock_common *)ssk, &local);
if (!addresses_equal(&local, addr, addr->port))
@@ -682,9 +678,7 @@ int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
spin_unlock_bh(&msk->pm.lock);
pr_debug("send ack for mp_prio");
- slow = lock_sock_fast(ssk);
- tcp_send_ack(ssk);
- unlock_sock_fast(ssk, slow);
+ mptcp_subflow_send_ack(ssk);
spin_lock_bh(&msk->pm.lock);
return 0;
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index a4c6e37e07c9..2602f1386160 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -440,19 +440,22 @@ static bool tcp_can_send_ack(const struct sock *ssk)
(TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE | TCPF_LISTEN));
}
+void mptcp_subflow_send_ack(struct sock *ssk)
+{
+ bool slow;
+
+ slow = lock_sock_fast(ssk);
+ if (tcp_can_send_ack(ssk))
+ tcp_send_ack(ssk);
+ unlock_sock_fast(ssk, slow);
+}
+
static void mptcp_send_ack(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
- mptcp_for_each_subflow(msk, subflow) {
- struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
- bool slow;
-
- slow = lock_sock_fast(ssk);
- if (tcp_can_send_ack(ssk))
- tcp_send_ack(ssk);
- unlock_sock_fast(ssk, slow);
- }
+ mptcp_for_each_subflow(msk, subflow)
+ mptcp_subflow_send_ack(mptcp_subflow_tcp_sock(subflow));
}
static void mptcp_subflow_cleanup_rbuf(struct sock *ssk)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 64c9a30e0871..d3e6fd1615f1 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -573,6 +573,7 @@ void __init mptcp_subflow_init(void);
void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how);
void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
struct mptcp_subflow_context *subflow);
+void mptcp_subflow_send_ack(struct sock *ssk);
void mptcp_subflow_reset(struct sock *ssk);
void mptcp_sock_graft(struct sock *sk, struct socket *parent);
struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk);