tls: make sure to abort the stream if headers are bogus

JIRA: https://issues.redhat.com/browse/RHEL-115640

commit 0aeb54a
Author: Jakub Kicinski <kuba@kernel.org>
Date:   Tue Sep 16 17:28:13 2025 -0700

    tls: make sure to abort the stream if headers are bogus

    Normally we wait for the socket to buffer up the whole record
    before we service it. If the socket has a tiny buffer, however,
    we read out the data sooner, to prevent connection stalls.
    Make sure that we abort the connection when we find out late
    that the record is actually invalid. Retrying the parsing is
    fine in itself but since we copy some more data each time
    before we parse we can overflow the allocated skb space.

    Constructing a scenario in which we're under pressure without
    enough data in the socket to parse the length upfront is quite
    hard. syzbot figured out a way to do this by serving us the header
    in small OOB sends, and then filling in the recvbuf with a large
    normal send.

    Make sure that tls_rx_msg_size() aborts strp, if we reach
    an invalid record there's really no way to recover.

    Reported-by: Lee Jones <lee@kernel.org>
    Fixes: 84c61fe ("tls: rx: do not use the standard strparser")
    Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Link: https://patch.msgid.link/20250917002814.1743558-1-kuba@kernel.org
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Signed-off-by: Sabrina Dubroca <sdubroca@redhat.com>

Author: Sabrina Dubroca

net/tls/tls.h

@@ -139,6 +139,7 @@ void update_sk_prot(struct sock *sk, struct tls_context *ctx);
 
 int wait_on_pending_writer(struct sock *sk, long *timeo);
 void tls_err_abort(struct sock *sk, int err);
+void tls_strp_abort_strp(struct tls_strparser *strp, int err);
 
 int init_prot_info(struct tls_prot_info *prot,
 		   const struct tls_crypto_info *crypto_info,

net/tls/tls_strp.c

@@ -12,7 +12,7 @@
 
 static struct workqueue_struct *tls_strp_wq;
 
-static void tls_strp_abort_strp(struct tls_strparser *strp, int err)
+void tls_strp_abort_strp(struct tls_strparser *strp, int err)
 {
 	if (strp->stopped)
 		return;
@@ -210,11 +210,17 @@ static int tls_strp_copyin_frag(struct tls_strparser *strp, struct sk_buff *skb,
 				struct sk_buff *in_skb, unsigned int offset,
 				size_t in_len)
 {
+	unsigned int nfrag = skb->len / PAGE_SIZE;
 	size_t len, chunk;
 	skb_frag_t *frag;
 	int sz;
 
-	frag = &skb_shinfo(skb)->frags[skb->len / PAGE_SIZE];
+	if (unlikely(nfrag >= skb_shinfo(skb)->nr_frags)) {
+		DEBUG_NET_WARN_ON_ONCE(1);
+		return -EMSGSIZE;
+	}
+
+	frag = &skb_shinfo(skb)->frags[nfrag];
 
 	len = in_len;
 	/* First make sure we got the header */
@@ -519,10 +525,8 @@ static int tls_strp_read_sock(struct tls_strparser *strp)
 	tls_strp_load_anchor_with_queue(strp, inq);
 	if (!strp->stm.full_len) {
 		sz = tls_rx_msg_size(strp, strp->anchor);
-		if (sz < 0) {
-			tls_strp_abort_strp(strp, sz);
+		if (sz < 0)
 			return sz;
-		}
 
 		strp->stm.full_len = sz;
 

net/tls/tls_sw.c

@@ -2460,8 +2460,7 @@ int tls_rx_msg_size(struct tls_strparser *strp, struct sk_buff *skb)
 	return data_len + TLS_HEADER_SIZE;
 
 read_failure:
-	tls_err_abort(strp->sk, ret);
-
+	tls_strp_abort_strp(strp, ret);
 	return ret;
 }