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Code Issues Releases Wiki Activity

Prevent out of bounds (3)

This commit is contained in:
M66B 2019-12-19 14:51:43 +01:00
parent 5978352b2d
commit e98d5ef6a9
1 changed files with 14 additions and 3 deletions
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17
app/src/main/jni/netguard/dns.c
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@ -29,11 +29,17 @@ int32_t get_qname(const uint8_t *data, const size_t datalen, uint16_t off, char
uint8_t noff = 0;
uint16_t ptr = off;
uint8_t len = *(data + ptr);
uint8_t count = 0;
while (len) {
if (count++ > 25)
break;
if (len & 0xC0) {
uint16_t jump = (uint16_t) ((len & 0x3F) * 256 + *(data + ptr + 1));
if (jump >= datalen)
if (jump >= datalen) {
log_android(ANDROID_LOG_DEBUG, "DNS invalid jump");
break;
}
ptr = jump;
len = *(data + ptr);
log_android(ANDROID_LOG_DEBUG, "DNS qname compression ptr %d len %d", ptr, len);
@ -41,12 +47,17 @@ int32_t get_qname(const uint8_t *data, const size_t datalen, uint16_t off, char
c = 1;
off += 2;
}
} else if (ptr + 1 + len <= datalen && noff + len <= DNS_QNAME_MAX) {
} else if (ptr + 1 + len < datalen && noff + len <= DNS_QNAME_MAX) {
memcpy(qname + noff, data + ptr + 1, len);
*(qname + noff + len) = '.';
noff += (len + 1);
ptr += (len + 1);
uint16_t jump = (uint16_t) (ptr + 1 + len);
if (jump >= datalen) {
log_android(ANDROID_LOG_DEBUG, "DNS invalid jump");
break;
}
ptr = jump;
len = *(data + ptr);
} else
break;