net: selftests: initialize TCP header and skb payload with zero

Zero-initialize TCP header via memset() to avoid garbage values that
may affect checksum or behavior during test transmission.

Also zero-fill allocated payload and padding regions using memset()
after skb_put(), ensuring deterministic content for all outgoing
test packets.

Fixes: 3e1e58d64c3d ("net: add generic selftest support")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: stable@vger.kernel.org
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250416160125.2914724-1-o.rempel@pengutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/core/selftests.c b/net/core/selftests.c
index e99ae983fca9bb57b6955bf0b6fb365f93e4445f..35f807ea995235bf2e08779eefa6a226c0885414 100644 (file)
--- a/net/core/selftests.c
+++ b/net/core/selftests.c
@@ -100,10 +100,10 @@ static struct sk_buff *net_test_get_skb(struct net_device *ndev,
        ehdr->h_proto = htons(ETH_P_IP);
 
        if (attr->tcp) {
+               memset(thdr, 0, sizeof(*thdr));
                thdr->source = htons(attr->sport);
                thdr->dest = htons(attr->dport);
                thdr->doff = sizeof(struct tcphdr) / 4;
-               thdr->check = 0;
        } else {
                uhdr->source = htons(attr->sport);
                uhdr->dest = htons(attr->dport);
@@ -144,10 +144,18 @@ static struct sk_buff *net_test_get_skb(struct net_device *ndev,
        attr->id = net_test_next_id;
        shdr->id = net_test_next_id++;
 
-       if (attr->size)
-               skb_put(skb, attr->size);
-       if (attr->max_size && attr->max_size > skb->len)
-               skb_put(skb, attr->max_size - skb->len);
+       if (attr->size) {
+               void *payload = skb_put(skb, attr->size);
+
+               memset(payload, 0, attr->size);
+       }
+
+       if (attr->max_size && attr->max_size > skb->len) {
+               size_t pad_len = attr->max_size - skb->len;
+               void *pad = skb_put(skb, pad_len);
+
+               memset(pad, 0, pad_len);
+       }
 
        skb->csum = 0;
        skb->ip_summed = CHECKSUM_PARTIAL;