tcp_comp: Avoiding the null pointer problem of ctx in comp_stream_read

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I45UYC?from=project-issue
CVE: NA

-------------------------------------------------

In comp_stream_read ctx might be null, add null check to avoid oops. And delete
unnecessary tcp_comp_err_abort.
Signed-off-by: NWang Yufen <wangyufen@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NLu Wei <luwei32@huawei.com>
Reviewed-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/ipv4/tcp_comp.c

@@ -699,8 +699,6 @@ static int tcp_comp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		if (!ctx->rx.decompressed) {
 			err = tcp_comp_decompress(sk, skb);
 			if (err < 0) {
-				if (err != -ENOSPC)
-					tcp_comp_err_abort(sk, EBADMSG);
 				goto recv_end;
 			}
 			ctx->rx.decompressed = true;
@@ -734,6 +732,9 @@ bool comp_stream_read(const struct sock *sk)
 {
 	struct tcp_comp_context *ctx = comp_get_ctx(sk);
 
+	if (!ctx)
+		return false;
+
 	if (ctx->rx.pkt)
 		return true;