pktgen: Dont leak kernel memory

While playing with pktgen, I realized IP ID was not filled and a
random value was taken, possibly leaking 2 bytes of kernel memory.
 
We can use an increasing ID, this can help diagnostics anyway.

Also clear packet payload, instead of leaking kernel memory.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 5 deletions

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 86acdba0a97d..6eb8d47cbf3a 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -335,6 +335,7 @@ struct pktgen_dev {
         __u32 cur_src_mac_offset;
         __be32 cur_saddr;
         __be32 cur_daddr;
+        __u16 ip_id;
         __u16 cur_udp_dst;
         __u16 cur_udp_src;
         __u16 cur_queue_map;
@@ -2630,6 +2631,8 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
         iph->protocol = IPPROTO_UDP;    /* UDP */
         iph->saddr = pkt_dev->cur_saddr;
         iph->daddr = pkt_dev->cur_daddr;
+        iph->id = htons(pkt_dev->ip_id);
+        pkt_dev->ip_id++;
         iph->frag_off = 0;
         iplen = 20 + 8 + datalen;
         iph->tot_len = htons(iplen);
@@ -2641,24 +2644,26 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
         skb->dev = odev;
         skb->pkt_type = PACKET_HOST;
 
-        if (pkt_dev->nfrags <= 0)
+        if (pkt_dev->nfrags <= 0) {
                 pgh = (struct pktgen_hdr *)skb_put(skb, datalen);
-        else {
+                memset(pgh + 1, 0, datalen - sizeof(struct pktgen_hdr));
+        } else {
                 int frags = pkt_dev->nfrags;
-                int i;
+                int i, len;
 
                 pgh = (struct pktgen_hdr *)(((char *)(udph)) + 8);
 
                 if (frags > MAX_SKB_FRAGS)
                         frags = MAX_SKB_FRAGS;
                 if (datalen > frags * PAGE_SIZE) {
-                        skb_put(skb, datalen - frags * PAGE_SIZE);
+                        len = datalen - frags * PAGE_SIZE;
+                        memset(skb_put(skb, len), 0, len);
                         datalen = frags * PAGE_SIZE;
                 }
 
                 i = 0;
                 while (datalen > 0) {
-                        struct page *page = alloc_pages(GFP_KERNEL, 0);
+                        struct page *page = alloc_pages(GFP_KERNEL | __GFP_ZERO, 0);
                         skb_shinfo(skb)->frags[i].page = page;
                         skb_shinfo(skb)->frags[i].page_offset = 0;
                         skb_shinfo(skb)->frags[i].size =