Amazing-Mirror/fragattacks
1
0
Fork 0
mirror of https://github.com/vanhoefm/fragattacks.git synced 2024-11-25 00:38:24 -05:00
Code Issues Projects Releases Wiki Activity

TLS: Be more careful in X.509 Time parsing

Browse Source 
sscanf() can apparently read beyond the end of the buffer even if the
maximum length of the integer is specified in the format string. Replace
this parsing mechanism with helper functions that use sscanf() with NUL
terminated string to avoid this.

Credit to OSS-Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15158
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2019-06-09 04:41:15 +03:00
parent d438b4a3ce
commit a6ed414c82
1 changed files with 50 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
src/tls/x509v3.c
View File

@ -538,9 +538,43 @@ done:
} }
static int parse_uint2(const char *pos, size_t len)
{
char buf[3];
int ret;
if (len < 2)
return -1;
buf[0] = pos[0];
buf[1] = pos[1];
buf[2] = 0x00;
if (sscanf(buf, "%2d", &ret) != 1)
return -1;
return ret;
}
static int parse_uint4(const char *pos, size_t len)
{
char buf[5];
int ret;
if (len < 4)
return -1;
buf[0] = pos[0];
buf[1] = pos[1];
buf[2] = pos[2];
buf[3] = pos[3];
buf[4] = 0x00;
if (sscanf(buf, "%4d", &ret) != 1)
return -1;
return ret;
}
int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val) int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val)
{ {
const char *pos; const char *pos, *end;
int year, month, day, hour, min, sec; int year, month, day, hour, min, sec;
/* /*
@ -554,6 +588,7 @@ int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val)
*/ */
pos = (const char *) buf; pos = (const char *) buf;
end = pos + len;
switch (asn1_tag) { switch (asn1_tag) {
case ASN1_TAG_UTCTIME: case ASN1_TAG_UTCTIME:
@ -562,7 +597,8 @@ int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val)
"UTCTime format", buf, len); "UTCTime format", buf, len);
return -1; return -1;
} }
if (sscanf(pos, "%02d", &year) != 1) { year = parse_uint2(pos, end - pos);
if (year < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse " wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse "
"UTCTime year", buf, len); "UTCTime year", buf, len);
return -1; return -1;
@ -579,7 +615,8 @@ int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val)
"GeneralizedTime format", buf, len); "GeneralizedTime format", buf, len);
return -1; return -1;
} }
if (sscanf(pos, "%04d", &year) != 1) { year = parse_uint4(pos, end - pos);
if (year < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse " wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse "
"GeneralizedTime year", buf, len); "GeneralizedTime year", buf, len);
return -1; return -1;
@ -592,35 +629,40 @@ int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val)
return -1; return -1;
} }
if (sscanf(pos, "%02d", &month) != 1) { month = parse_uint2(pos, end - pos);
if (month < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time " wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time "
"(month)", buf, len); "(month)", buf, len);
return -1; return -1;
} }
pos += 2; pos += 2;
if (sscanf(pos, "%02d", &day) != 1) { day = parse_uint2(pos, end - pos);
if (day < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time " wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time "
"(day)", buf, len); "(day)", buf, len);
return -1; return -1;
} }
pos += 2; pos += 2;
if (sscanf(pos, "%02d", &hour) != 1) { hour = parse_uint2(pos, end - pos);
if (hour < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time " wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time "
"(hour)", buf, len); "(hour)", buf, len);
return -1; return -1;
} }
pos += 2; pos += 2;
if (sscanf(pos, "%02d", &min) != 1) { min = parse_uint2(pos, end - pos);
if (min < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time " wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time "
"(min)", buf, len); "(min)", buf, len);
return -1; return -1;
} }
pos += 2; pos += 2;
if (sscanf(pos, "%02d", &sec) != 1) { sec = parse_uint2(pos, end - pos);
if (sec < 0) {
wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time " wpa_hexdump_ascii(MSG_DEBUG, "X509: Failed to parse Time "
"(sec)", buf, len); "(sec)", buf, len);
return -1; return -1;