pimd: When receiving a packet be more careful with length in pim_pim_packet

a) If the length passed is the header length then it is possible that
assignment of data will happen without data actually existing.

b) Just move the assignment to after we ensure that the pim packet
received is the minimum possible length that can be received.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>
(cherry picked from commit 3163c64d2893b5411d299952ff16dfc05e2c7a86)

diff --git a/pimd/pim_pim.c b/pimd/pim_pim.c
index 4a272a4802b708e2b5309be0300748c16d9d4900..a4c9178bb9fc998721387c2de775e28b8cedb7ce 100644 (file)
--- a/pimd/pim_pim.c
+++ b/pimd/pim_pim.c
@@ -155,7 +155,7 @@ int pim_pim_packet(struct interface *ifp, uint8_t *buf, size_t len,
        bool   no_fwd;
 
 #if PIM_IPV == 4
-       if (len < sizeof(*ip_hdr)) {
+       if (len <= sizeof(*ip_hdr)) {
                if (PIM_DEBUG_PIM_PACKETS)
                        zlog_debug(
                                "PIM packet size=%zu shorter than minimum=%zu",
@@ -189,7 +189,6 @@ int pim_pim_packet(struct interface *ifp, uint8_t *buf, size_t len,
        iovp->iov_len = pim_msg_len;
        iovp++;
 
-       header = (struct pim_msg_header *)pim_msg;
        if (pim_msg_len < PIM_PIM_MIN_LEN) {
                if (PIM_DEBUG_PIM_PACKETS)
                        zlog_debug(
@@ -197,6 +196,7 @@ int pim_pim_packet(struct interface *ifp, uint8_t *buf, size_t len,
                                pim_msg_len, PIM_PIM_MIN_LEN);
                return -1;
        }
+       header = (struct pim_msg_header *)pim_msg;
 
        if (header->ver != PIM_PROTO_VERSION) {
                if (PIM_DEBUG_PIM_PACKETS)