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P2P SD: Avoid undefined behavior in pointer arithmetic

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Reorder terms in a way that no invalid pointers are generated with
pos+len operations. end-pos is always defined (with a valid pos pointer)
while pos+len could end up pointing beyond the end pointer which would
be undefined behavior.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-10-18 12:11:45 +03:00
parent 619fdfacc4
commit f758ae7665
1 changed files with 9 additions and 9 deletions
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18
wpa_supplicant/p2p_supplicant_sd.c
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@ -48,7 +48,7 @@ static int p2p_sd_dns_uncompress_label(char **upos, char *uend, u8 *start,
u8 *spos_tmp; u8 *spos_tmp;
/* Offset */ /* Offset */
if (*spos + 2 > end) { if (end - *spos < 2) {
wpa_printf(MSG_DEBUG, "P2P: No room for full " wpa_printf(MSG_DEBUG, "P2P: No room for full "
"DNS offset field"); "DNS offset field");
return -1; return -1;
@ -74,14 +74,14 @@ static int p2p_sd_dns_uncompress_label(char **upos, char *uend, u8 *start,
return 0; return 0;
(*spos)++; (*spos)++;
if (*spos + len > end) { if (len > end - *spos) {
wpa_printf(MSG_DEBUG, "P2P: Invalid domain name " wpa_printf(MSG_DEBUG, "P2P: Invalid domain name "
"sequence - no room for label with length " "sequence - no room for label with length "
"%u", len); "%u", len);
return -1; return -1;
} }
if (*upos + len + 2 > uend) if (len + 2 > uend - *upos)
return -2; return -2;
os_memcpy(*upos, *spos, len); os_memcpy(*upos, *spos, len);
@ -722,11 +722,11 @@ void wpas_sd_request(void *ctx, int freq, const u8 *sa, u8 dialog_token,
if (resp == NULL) if (resp == NULL)
return; return;
while (pos + 1 < end) { while (end - pos > 1) {
wpa_printf(MSG_DEBUG, "P2P: Service Request TLV"); wpa_printf(MSG_DEBUG, "P2P: Service Request TLV");
slen = WPA_GET_LE16(pos); slen = WPA_GET_LE16(pos);
pos += 2; pos += 2;
if (pos + slen > end || slen < 2) { if (slen > end - pos || slen < 2) {
wpa_printf(MSG_DEBUG, "P2P: Unexpected Query Data " wpa_printf(MSG_DEBUG, "P2P: Unexpected Query Data "
"length"); "length");
wpabuf_free(resp); wpabuf_free(resp);
@ -827,10 +827,10 @@ static void wpas_sd_p2ps_serv_response(struct wpa_supplicant *wpa_s,
u8 svc_len; u8 svc_len;
/* Sanity check fixed length+svc_str */ /* Sanity check fixed length+svc_str */
if (pos + 6 >= tlv_end) if (6 >= tlv_end - pos)
break; break;
svc_len = pos[6]; svc_len = pos[6];
if (pos + svc_len + 10 > tlv_end) if (svc_len + 10 > tlv_end - pos)
break; break;
/* Advertisement ID */ /* Advertisement ID */
@ -917,13 +917,13 @@ void wpas_sd_response(void *ctx, const u8 *sa, u16 update_indic,
} }
} }
while (pos < end) { while (end - pos >= 2) {
u8 srv_proto, srv_trans_id, status; u8 srv_proto, srv_trans_id, status;
wpa_printf(MSG_DEBUG, "P2P: Service Response TLV"); wpa_printf(MSG_DEBUG, "P2P: Service Response TLV");
slen = WPA_GET_LE16(pos); slen = WPA_GET_LE16(pos);
pos += 2; pos += 2;
if (pos + slen > end || slen < 3) { if (slen > end - pos || slen < 3) {
wpa_printf(MSG_DEBUG, "P2P: Unexpected Response Data " wpa_printf(MSG_DEBUG, "P2P: Unexpected Response Data "
"length"); "length");
return; return;