vallen is verified to be less than len, therefore, it can never

be the case that `vallen >= len + sizeof(rhostname)`. This PR fixes the check so the `rhostname` array does not overflow. Reported-by: Github Security Lab <[email protected]> Signed-off-by: Alvaro Muñoz <[email protected]>
spacemeowx2 · Mar 7, 2020 · 42be6b2 · 42be6b2
1 parent c4f2d75
commit 42be6b2
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/lwip/src/netif/ppp/eap.c b/lwip/src/netif/ppp/eap.c
@@ -1417,7 +1417,7 @@ static void eap_request(ppp_pcb *pcb, u_char *inp, int id, int len) {
 		}
 
 		/* Not so likely to happen. */
-		if (vallen >= len + sizeof (rhostname)) {
+		if (len - vallen >= sizeof (rhostname)) {
 			ppp_dbglog("EAP: trimming really long peer name down");
 			MEMCPY(rhostname, inp + vallen, sizeof (rhostname) - 1);
 			rhostname[sizeof (rhostname) - 1] = '\0';
@@ -1845,7 +1845,7 @@ static void eap_response(ppp_pcb *pcb, u_char *inp, int id, int len) {
 		}
 
 		/* Not so likely to happen. */
-		if (vallen >= len + sizeof (rhostname)) {
+		if (len - vallen >= sizeof (rhostname)) {
 			ppp_dbglog("EAP: trimming really long peer name down");
 			MEMCPY(rhostname, inp + vallen, sizeof (rhostname) - 1);
 			rhostname[sizeof (rhostname) - 1] = '\0';