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Avoid undefined behavior in pointer arithmetic in BSS IE parsing

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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 11:43:24 +03:00
parent 67fea55ca2
commit 1f32a23962
1 changed files with 10 additions and 10 deletions
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20
wpa_supplicant/bss.c
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@ -1024,8 +1024,8 @@ const u8 * wpa_bss_get_ie(const struct wpa_bss *bss, u8 ie)
pos = (const u8 *) (bss + 1); pos = (const u8 *) (bss + 1);
end = pos + bss->ie_len; end = pos + bss->ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == ie) if (pos[0] == ie)
return pos; return pos;
@ -1052,8 +1052,8 @@ const u8 * wpa_bss_get_vendor_ie(const struct wpa_bss *bss, u32 vendor_type)
pos = (const u8 *) (bss + 1); pos = (const u8 *) (bss + 1);
end = pos + bss->ie_len; end = pos + bss->ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2])) vendor_type == WPA_GET_BE32(&pos[2]))
@ -1089,8 +1089,8 @@ const u8 * wpa_bss_get_vendor_ie_beacon(const struct wpa_bss *bss,
pos += bss->ie_len; pos += bss->ie_len;
end = pos + bss->beacon_ie_len; end = pos + bss->beacon_ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2])) vendor_type == WPA_GET_BE32(&pos[2]))
@ -1125,8 +1125,8 @@ struct wpabuf * wpa_bss_get_vendor_ie_multi(const struct wpa_bss *bss,
pos = (const u8 *) (bss + 1); pos = (const u8 *) (bss + 1);
end = pos + bss->ie_len; end = pos + bss->ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2])) vendor_type == WPA_GET_BE32(&pos[2]))
@ -1170,8 +1170,8 @@ struct wpabuf * wpa_bss_get_vendor_ie_multi_beacon(const struct wpa_bss *bss,
pos += bss->ie_len; pos += bss->ie_len;
end = pos + bss->beacon_ie_len; end = pos + bss->beacon_ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2])) vendor_type == WPA_GET_BE32(&pos[2]))