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Prevent potential integer overflow when computing PACKET_OID_DATA allocation size #1647

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Prevent potential integer overflow when computing PACKET_OID_DATA allocation size #1647

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38 changes: 31 additions & 7 deletions pcap-npf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -196,13 +196,24 @@ oid_get_request(ADAPTER *adapter, bpf_u_int32 oid, void *data, size_t *lenp,
PACKET_OID_DATA *oid_data_arg;

/*
* Allocate a PACKET_OID_DATA structure to hand to PacketRequest().
* It should be big enough to hold "*lenp" bytes of data;
*/
oid_data_arg = malloc(PACKET_OID_DATA_LENGTH(*lenp));
* Allocate a PACKET_OID_DATA structure to hand to PacketRequest().
* It should be big enough to hold "*lenp" bytes of data.
* Check for overflow in the size calculation.
*/
size_t alloc_size;

if (*lenp > SIZE_MAX - offsetof(PACKET_OID_DATA, Data)) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"OID request length too large");
return (PCAP_ERROR);
}

alloc_size = offsetof(PACKET_OID_DATA, Data) + *lenp;

oid_data_arg = malloc(alloc_size);
if (oid_data_arg == NULL) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Couldn't allocate argument buffer for PacketRequest");
"Couldn't allocate argument buffer for PacketRequest");
return (PCAP_ERROR);
}

Expand Down Expand Up @@ -396,7 +407,20 @@ pcap_oid_set_request_npf(pcap_t *p, bpf_u_int32 oid, const void *data,
* Allocate a PACKET_OID_DATA structure to hand to PacketRequest().
* It should be big enough to hold "*lenp" bytes of data;
*/
oid_data_arg = malloc(PACKET_OID_DATA_LENGTH(*lenp));
size_t alloc_size;

/*
* Prevent integer overflow when computing allocation size.
*/
if (*lenp > SIZE_MAX - offsetof(PACKET_OID_DATA, Data)) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"OID request length too large");
return (PCAP_ERROR);
}

alloc_size = offsetof(PACKET_OID_DATA, Data) + *lenp;

oid_data_arg = malloc(alloc_size);
if (oid_data_arg == NULL) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"Couldn't allocate argument buffer for PacketRequest");
Expand Down Expand Up @@ -2534,4 +2558,4 @@ pcap_lib_version(void)
}
return (pcap_lib_version_string);
}
#endif /* HAVE_VERSION_H */
#endif /* HAVE_VERSION_H */