Commit f6bff34f authored by Sebastian Krahmer's avatar Sebastian Krahmer Committed by Peter Jones

shim buffer overflow on ipv6 option parsing

parent 597dd839
......@@ -108,29 +108,34 @@ BOOLEAN findNetboot(EFI_HANDLE device)
static CHAR8 *get_v6_bootfile_url(EFI_PXE_BASE_CODE_DHCPV6_PACKET *pkt)
{
void *optr;
EFI_DHCP6_PACKET_OPTION *option;
CHAR8 *url;
UINT32 urllen;
void *optr = NULL, *end = NULL;
EFI_DHCP6_PACKET_OPTION *option = NULL;
CHAR8 *url = NULL;
UINT32 urllen = 0;
optr = pkt->DhcpOptions;
end = optr + sizeof(pkt->DhcpOptions);
for(;;) {
for (;;) {
option = (EFI_DHCP6_PACKET_OPTION *)optr;
if (ntohs(option->OpCode) == 0)
return NULL;
break;
if (ntohs(option->OpCode) == 59) {
/* This is the bootfile url option */
urllen = ntohs(option->Length);
url = AllocateZeroPool(urllen+1);
if ((void *)(option->Data + urllen) > end)
break;
url = AllocateZeroPool(urllen + 1);
if (!url)
return NULL;
break;
memcpy(url, option->Data, urllen);
return url;
}
optr += 4 + ntohs(option->Length);
if (optr + sizeof(EFI_DHCP6_PACKET_OPTION) > end)
break;
}
return NULL;
......@@ -156,45 +161,60 @@ static CHAR16 str2ns(CHAR8 *str)
static CHAR8 *str2ip6(CHAR8 *str)
{
UINT8 i, j, p;
size_t len;
CHAR8 *a, *b, t;
static UINT16 ip[8];
UINT8 i = 0, j = 0, p = 0;
size_t len = 0, dotcount = 0;
enum { MAX_IP6_DOTS = 7 };
CHAR8 *a = NULL, *b = NULL, t = 0;
static UINT16 ip[8];
for(i=0; i < 8; i++) {
ip[i] = 0;
}
len = strlen(str);
a = b = str;
for(i=p=0; i < len; i++, b++) {
if (*b != ':')
continue;
*b = '\0';
ip[p++] = str2ns(a);
*b = ':';
a = b + 1;
if ( *(b+1) == ':' )
break;
}
a = b = (str + len);
for(j=len, p=7; j > i; j--, a--) {
if (*a != ':')
continue;
t = *b;
*b = '\0';
ip[p--] = str2ns(a+1);
*b = t;
b = a;
}
return (CHAR8 *)ip;
memset(ip, 0, sizeof(ip));
/* Count amount of ':' to prevent overflows.
* max. count = 7. Returns an invalid ip6 that
* can be checked against
*/
for (a = str; *a != 0; ++a) {
if (*a == ':')
++dotcount;
}
if (dotcount > MAX_IP6_DOTS)
return (CHAR8 *)ip;
len = strlen(str);
a = b = str;
for (i = p = 0; i < len; i++, b++) {
if (*b != ':')
continue;
*b = '\0';
ip[p++] = str2ns(a);
*b = ':';
a = b + 1;
if (b[1] == ':' )
break;
}
a = b = (str + len);
for (j = len, p = 7; j > i; j--, a--) {
if (*a != ':')
continue;
t = *b;
*b = '\0';
ip[p--] = str2ns(a+1);
*b = t;
b = a;
}
return (CHAR8 *)ip;
}
static BOOLEAN extract_tftp_info(CHAR8 *url)
{
CHAR8 *start, *end;
CHAR8 ip6str[40];
CHAR8 ip6inv[16];
CHAR8 *template = (CHAR8 *)translate_slashes(DEFAULT_LOADER_CHAR);
// to check against str2ip6() errors
memset(ip6inv, 0, sizeof(ip6inv));
if (strncmp((UINT8 *)url, (UINT8 *)"tftp://", 7)) {
Print(L"URLS MUST START WITH tftp://\n");
return FALSE;
......@@ -209,7 +229,7 @@ static BOOLEAN extract_tftp_info(CHAR8 *url)
end = start;
while ((*end != '\0') && (*end != ']')) {
end++;
if (end - start > 39) {
if (end - start >= (int)sizeof(ip6str)) {
Print(L"TFTP URL includes malformed IPv6 address\n");
return FALSE;
}
......@@ -218,10 +238,12 @@ static BOOLEAN extract_tftp_info(CHAR8 *url)
Print(L"TFTP SERVER MUST BE ENCLOSED IN [..]\n");
return FALSE;
}
memset(ip6str, 0, 40);
memset(ip6str, 0, sizeof(ip6str));
memcpy(ip6str, start, end - start);
end++;
memcpy(&tftp_addr.v6, str2ip6(ip6str), 16);
if (memcmp(&tftp_addr.v6, ip6inv, sizeof(ip6inv)) == 0)
return FALSE;
full_path = AllocateZeroPool(strlen(end)+strlen(template)+1);
if (!full_path)
return FALSE;
......
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