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Merge branch 'input-validation'

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Merge PR #472
This commit is contained in:
Mészáros Mihály 2020-02-18 14:39:04 +01:00
commit c534eaef41
1 changed files with 39 additions and 5 deletions
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42
src/client/ns_turn_msg.c
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@ -384,7 +384,14 @@ int stun_get_command_message_len_str(const uint8_t* buf, size_t len)
{ {
if (len < STUN_HEADER_LENGTH) if (len < STUN_HEADER_LENGTH)
return -1; return -1;
return (int) (nswap16(((const uint16_t*)(buf))[1]) + STUN_HEADER_LENGTH);
/* Validate the size the buffer claims to be */
int bufLen = (int) (nswap16(((const uint16_t*)(buf))[1]) + STUN_HEADER_LENGTH);
if (bufLen > len) {
return -1;
}
return bufLen;
} }
static int stun_set_command_message_len_str(uint8_t* buf, int len) { static int stun_set_command_message_len_str(uint8_t* buf, int len) {
@ -1375,10 +1382,34 @@ stun_attr_ref stun_attr_get_first_by_type_str(const uint8_t* buf, size_t len, ui
return NULL; return NULL;
} }
static stun_attr_ref stun_attr_check_valid(stun_attr_ref attr, size_t remaining) {
if(remaining >= 4) {
/* Read the size of the attribute */
int attrlen = stun_attr_get_len(attr);
remaining -= 4;
/* Round to boundary */
uint16_t rem4 = ((uint16_t)attrlen) & 0x0003;
if(rem4) {
attrlen = attrlen+4-(int)rem4;
}
/* Check that there's enough space remaining */
if(attrlen <= remaining) {
return attr;
}
}
return NULL;
}
stun_attr_ref stun_attr_get_first_str(const uint8_t* buf, size_t len) { stun_attr_ref stun_attr_get_first_str(const uint8_t* buf, size_t len) {
if(stun_get_command_message_len_str(buf,len)>STUN_HEADER_LENGTH) { int bufLen = stun_get_command_message_len_str(buf,len);
return (stun_attr_ref)(buf+STUN_HEADER_LENGTH); if(bufLen > STUN_HEADER_LENGTH) {
stun_attr_ref attr = (stun_attr_ref)(buf+STUN_HEADER_LENGTH);
return stun_attr_check_valid(attr, bufLen - STUN_HEADER_LENGTH);
} }
return NULL; return NULL;
@ -1394,8 +1425,11 @@ stun_attr_ref stun_attr_get_next_str(const uint8_t* buf, size_t len, stun_attr_r
if(rem4) { if(rem4) {
attrlen = attrlen+4-(int)rem4; attrlen = attrlen+4-(int)rem4;
} }
/* Note the order here: operations on attrlen are untrusted as they may overflow */
if(attrlen < end - (const uint8_t*)prev - 4) {
const uint8_t* attr_end=(const uint8_t*)prev+4+attrlen; const uint8_t* attr_end=(const uint8_t*)prev+4+attrlen;
if(attr_end<end) return attr_end; return stun_attr_check_valid(attr_end, end - attr_end);
}
return NULL; return NULL;
} }
} }