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libnetutil: Check dhcp respose packet length

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am: 61f25d4a36

Change-Id: Id5158c66d2ade871c90a2337fe867f977cefdca3
This commit is contained in:
tintin 2017-11-02 03:01:40 +00:00 committed by android-build-merger
commit cee6d38c55
1 changed files with 14 additions and 0 deletions
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14
libnetutils/packet.c
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@ -218,6 +218,20 @@ int receive_packet(int s, struct dhcp_msg *msg)
* to construct the pseudo header used in the checksum calculation.
*/
dhcp_size = ntohs(packet.udp.len) - sizeof(packet.udp);
/*
* check validity of dhcp_size.
* 1) cannot be negative or zero.
* 2) src buffer contains enough bytes to copy
* 3) cannot exceed destination buffer
*/
if ((dhcp_size <= 0) ||
((int)(nread - sizeof(struct iphdr) - sizeof(struct udphdr)) < dhcp_size) ||
((int)sizeof(struct dhcp_msg) < dhcp_size)) {
#if VERBOSE
ALOGD("Malformed Packet");
#endif
return -1;
}
saddr = packet.ip.saddr;
daddr = packet.ip.daddr;
nread = ntohs(packet.ip.tot_len);