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-rw-r--r--src/libsystemd-network/dhcp-protocol.h2
-rw-r--r--src/libsystemd-network/sd-dhcp-client.c16
2 files changed, 13 insertions, 5 deletions
diff --git a/src/libsystemd-network/dhcp-protocol.h b/src/libsystemd-network/dhcp-protocol.h
index 260508fbbd..4d87891ff1 100644
--- a/src/libsystemd-network/dhcp-protocol.h
+++ b/src/libsystemd-network/dhcp-protocol.h
@@ -60,7 +60,7 @@ typedef struct DHCPPacket DHCPPacket;
#define DHCP_IP_SIZE (int32_t)(sizeof(struct iphdr))
#define DHCP_IP_UDP_SIZE (int32_t)(sizeof(struct udphdr) + DHCP_IP_SIZE)
#define DHCP_MESSAGE_SIZE (int32_t)(sizeof(DHCPMessage))
-#define DHCP_MIN_OPTIONS_SIZE 308
+#define DHCP_MIN_OPTIONS_SIZE 308 /* spec says 312, but that includes the magic cookie */
#define DHCP_MAGIC_COOKIE (uint32_t)(0x63825363)
enum {
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index ac97e00772..ba44069f66 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -1186,8 +1186,12 @@ static int client_receive_message_udp(sd_event_source *s, int fd,
assert(client);
r = ioctl(fd, FIONREAD, &buflen);
- if (r < 0 || buflen <= 0)
- buflen = sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE;
+ if (r < 0)
+ return r;
+
+ if (buflen < 0)
+ /* this can't be right */
+ return -EIO;
message = malloc0(buflen);
if (!message)
@@ -1224,8 +1228,12 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
assert(client);
r = ioctl(fd, FIONREAD, &buflen);
- if (r < 0 || buflen <= 0)
- buflen = sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE;
+ if (r < 0)
+ return r;
+
+ if (buflen < 0)
+ /* this can't be right */
+ return -EIO;
packet = malloc0(buflen);
if (!packet)