fd1972099
Denys Vlasenko
2026-09-21
Subject
udhcpc: ensure packet.data.cookie exists before we access it
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Commit Diff GitHub →
networking/udhcp/dhcpc.c+7 -2
| @@ -900,7 +900,12 @@ static NOINLINE int d4_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) | |
| break; | |
| } | |
| - | if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) { |
| + | if (bytes < (int) ( |
| + | sizeof(packet.ip) + sizeof(packet.udp) |
| + | + offsetof(struct dhcp_packet, options) |
| + | /* DHCP requires option 255 is always present, IOW: at least one byte in options[]: */ |
| + | + 1 |
| + | )) { |
| log1s("packet is too short, ignoring"); | |
| return -2; | |
| } | |
| @@ -954,7 +959,7 @@ static NOINLINE int d4_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) | |
| packet.ip.tot_len = packet.udp.len; /* yes, this is needed */ | |
| check = packet.udp.check; | |
| packet.udp.check = 0; | |
| - | if (check && check != inet_cksum(&packet, bytes)) { |
| + | if (check != 0 && check != inet_cksum(&packet, bytes)) { |
| log1s("packet with bad UDP checksum, ignoring"); | |
| return -2; | |
| } | |