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nwfilter: Avoid memory alignment issues
The returned packet can have less strict alignment (u_char) than the struct (ether_header) we are casting it to, so to avoid alignment issues just copy the header into the struct on the stack. Signed-off-by: Martin Kletzander <mkletzan@redhat.com> Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>
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@ -384,7 +384,7 @@ learnIPAddressThread(void *arg)
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struct bpf_program fp;
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struct bpf_program fp;
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struct pcap_pkthdr header;
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struct pcap_pkthdr header;
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const u_char *packet;
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const u_char *packet;
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struct ether_header *ether_hdr;
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struct ether_header ether_hdr;
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struct ether_vlan_header *vlan_hdr;
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struct ether_vlan_header *vlan_hdr;
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virNWFilterIPAddrLearnReq *req = arg;
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virNWFilterIPAddrLearnReq *req = arg;
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uint32_t vmaddr = 0, bcastaddr = 0;
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uint32_t vmaddr = 0, bcastaddr = 0;
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@ -506,13 +506,14 @@ learnIPAddressThread(void *arg)
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}
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}
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if (header.len >= sizeof(struct ether_header)) {
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if (header.len >= sizeof(struct ether_header)) {
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ether_hdr = (struct ether_header*)packet;
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/* Avoid alignment issues */
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memcpy(ðer_hdr, packet, sizeof(struct ether_header));
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switch (ntohs(ether_hdr->ether_type)) {
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switch (ntohs(ether_hdr.ether_type)) {
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case ETHERTYPE_IP:
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case ETHERTYPE_IP:
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ethHdrSize = sizeof(struct ether_header);
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ethHdrSize = sizeof(struct ether_header);
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etherType = ntohs(ether_hdr->ether_type);
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etherType = ntohs(ether_hdr.ether_type);
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break;
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break;
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case ETHERTYPE_VLAN:
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case ETHERTYPE_VLAN:
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@ -528,7 +529,7 @@ learnIPAddressThread(void *arg)
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continue;
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continue;
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}
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}
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if (virMacAddrCmpRaw(&req->binding->mac, ether_hdr->ether_shost) == 0) {
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if (virMacAddrCmpRaw(&req->binding->mac, ether_hdr.ether_shost) == 0) {
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/* packets from the VM */
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/* packets from the VM */
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if (etherType == ETHERTYPE_IP &&
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if (etherType == ETHERTYPE_IP &&
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@ -568,9 +569,9 @@ learnIPAddressThread(void *arg)
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}
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}
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}
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}
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} else if (virMacAddrCmpRaw(&req->binding->mac,
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} else if (virMacAddrCmpRaw(&req->binding->mac,
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ether_hdr->ether_dhost) == 0 ||
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ether_hdr.ether_dhost) == 0 ||
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/* allow Broadcast replies from DHCP server */
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/* allow Broadcast replies from DHCP server */
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virMacAddrIsBroadcastRaw(ether_hdr->ether_dhost)) {
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virMacAddrIsBroadcastRaw(ether_hdr.ether_dhost)) {
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/* packets to the VM */
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/* packets to the VM */
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if (etherType == ETHERTYPE_IP &&
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if (etherType == ETHERTYPE_IP &&
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(header.len >= ethHdrSize +
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(header.len >= ethHdrSize +
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