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Avoid undefined behavior in pointer arithmetic in 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 02:22:34 +03:00
parent 7b5880fcf4
commit b6f961ab25
1 changed files with 6 additions and 6 deletions
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12
src/common/ieee802_11_common.c
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@ -398,8 +398,8 @@ int ieee802_11_ie_count(const u8 *ies, size_t ies_len)
pos = ies; pos = ies;
end = ies + ies_len; end = ies + ies_len;
while (pos + 2 <= end) { while (end - pos >= 2) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
count++; count++;
pos += 2 + pos[1]; pos += 2 + pos[1];
@ -419,8 +419,8 @@ struct wpabuf * ieee802_11_vendor_ie_concat(const u8 *ies, size_t ies_len,
end = ies + ies_len; end = ies + ies_len;
ie = NULL; ie = NULL;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
return NULL; return NULL;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
WPA_GET_BE32(&pos[2]) == oui_type) { WPA_GET_BE32(&pos[2]) == oui_type) {
@ -441,8 +441,8 @@ struct wpabuf * ieee802_11_vendor_ie_concat(const u8 *ies, size_t ies_len,
* There may be multiple vendor IEs in the message, so need to * There may be multiple vendor IEs in the message, so need to
* concatenate their data fields. * concatenate their data fields.
*/ */
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 &&
WPA_GET_BE32(&pos[2]) == oui_type) WPA_GET_BE32(&pos[2]) == oui_type)