FAILED: patch "[PATCH] tcp: add sanity tests to TCP_QUEUE_SEQ" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8811f4a9836e31c14ecdf79d9f3cb7c5d463265d Mon Sep 17 00:00:00 2001
From: Eric Dumazet <[email protected]>
Date: Mon, 1 Mar 2021 10:29:17 -0800
Subject: [PATCH] tcp: add sanity tests to TCP_QUEUE_SEQ

Qingyu Li reported a syzkaller bug where the repro changes RCV SEQ _after_ restoring data in the receive queue.

mprotect(0x4aa000, 12288, PROT_READ) = 0
mmap(0x1ffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x1ffff000
mmap(0x20000000, 16777216, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x20000000 mmap(0x21000000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x21000000
socket(AF_INET6, SOCK_STREAM, IPPROTO_IP) = 3
setsockopt(3, SOL_TCP, TCP_REPAIR, [1], 4) = 0
connect(3, {sa_family=AF_INET6, sin6_port=htons(0), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_scope_id=0}, 28) = 0 setsockopt(3, SOL_TCP, TCP_REPAIR_QUEUE, [1], 4) = 0
sendmsg(3, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="0x0000000000000003\0\0", iov_len=20}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20 setsockopt(3, SOL_TCP, TCP_REPAIR, [0], 4) = 0
setsockopt(3, SOL_TCP, TCP_QUEUE_SEQ, [128], 4) = 0
recvfrom(3, NULL, 20, 0, NULL, NULL) = -1 ECONNRESET (Connection reset by peer)

syslog shows:

[  111.205099] TCP recvmsg seq # bug 2: copied 80, seq 0, rcvnxt 80, fl 0
[  111.207894] WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:2343 tcp_recvmsg_locked+0x90e/0x29a0

This should not be allowed. TCP_QUEUE_SEQ should only be used when queues are empty.

This patch fixes this case, and the tx path as well.

Fixes ee9952831cfd ("tcp: Initial repair mode")

Signed-off-by Eric Dumazet <[email protected]>

Cc Pavel Emelyanov <[email protected]>

Link https://bugzilla.kernel.org/show_bug.cgi?id=212005

Reported-by Qingyu Li <[email protected]>

Signed-off-by David S. Miller <[email protected]>

net/ipv4/tcp.c +15 -8

index dfb6f286c1de..de7cc8445ac0 100644
@@ -3469,16 +3469,23 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
                break;
 
        case TCP_QUEUE_SEQ:
-               if (sk->sk_state != TCP_CLOSE)
+               if (sk->sk_state != TCP_CLOSE) {
                        err = -EPERM;
-               else if (tp->repair_queue == TCP_SEND_QUEUE)
-                       WRITE_ONCE(tp->write_seq, val);
-               else if (tp->repair_queue == TCP_RECV_QUEUE) {
-                       WRITE_ONCE(tp->rcv_nxt, val);
-                       WRITE_ONCE(tp->copied_seq, val);
-               }
-               else
+               } else if (tp->repair_queue == TCP_SEND_QUEUE) {
+                       if (!tcp_rtx_queue_empty(sk))
+                               err = -EPERM;
+                       else
+                               WRITE_ONCE(tp->write_seq, val);
+               } else if (tp->repair_queue == TCP_RECV_QUEUE) {
+                       if (tp->rcv_nxt != tp->copied_seq) {
+                               err = -EPERM;
+                       } else {
+                               WRITE_ONCE(tp->rcv_nxt, val);
+                               WRITE_ONCE(tp->copied_seq, val);
+                       }
+               } else {
                        err = -EINVAL;
+               }
                break;
 
        case TCP_REPAIR_OPTIONS: