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PPP: remove casts from unsigned (strlen return value) to signed when checking auth

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In theory, if provided username or password is over 0x80000000 byte long
(err...), casts to signed integer of strlen() return values is going to
return negative values breaking lengths checks.

Fix it by only using unsigned integer or size_t (guaranteed to be
unsigned) comparisons.
This commit is contained in:
Sylvain Rochet 2020-10-16 21:16:05 +02:00
parent 49bbc2d4bf
commit 729b3da96d
2 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/include/netif/ppp/ppp_impl.h
View File

@ -559,7 +559,7 @@ void start_networks(ppp_pcb *pcb); /* start all the network control protos */
void continue_networks(ppp_pcb *pcb); /* start network [ip, etc] control protos */
#if PPP_AUTH_SUPPORT
#if PPP_SERVER
int auth_check_passwd(ppp_pcb *pcb, char *auser, int userlen, char *apasswd, int passwdlen, const char **msg, int *msglen);
int auth_check_passwd(ppp_pcb *pcb, char *auser, unsigned int userlen, char *apasswd, unsigned int passwdlen, const char **msg, int *msglen);
/* check the user name and passwd against configuration */
void auth_peer_fail(ppp_pcb *pcb, int protocol);
/* peer failed to authenticate itself */

17
src/netif/ppp/auth.c
View File

@ -1003,13 +1003,13 @@ void continue_networks(ppp_pcb *pcb) {
* 1: Authentication succeeded.
* In either case, msg points to an appropriate message and msglen to the message len.
*/
int auth_check_passwd(ppp_pcb *pcb, char *auser, int userlen, char *apasswd, int passwdlen, const char **msg, int *msglen) {
int secretuserlen;
int secretpasswdlen;
int auth_check_passwd(ppp_pcb *pcb, char *auser, unsigned int userlen, char *apasswd, unsigned int passwdlen, const char **msg, int *msglen) {
size_t secretuserlen;
size_t secretpasswdlen;
if (pcb->settings.user && pcb->settings.passwd) {
secretuserlen = (int)strlen(pcb->settings.user);
secretpasswdlen = (int)strlen(pcb->settings.passwd);
secretuserlen = strlen(pcb->settings.user);
secretpasswdlen = strlen(pcb->settings.passwd);
if (secretuserlen == userlen
&& secretpasswdlen == passwdlen
&& !memcmp(auser, pcb->settings.user, userlen)
@ -1902,7 +1902,7 @@ have_srp_secret(client, server, need_ip, lacks_ipp)
* (We could be either client or server).
*/
int get_secret(ppp_pcb *pcb, const char *client, const char *server, char *secret, int *secret_len, int am_server) {
int len;
size_t len;
LWIP_UNUSED_ARG(server);
LWIP_UNUSED_ARG(am_server);
@ -1910,7 +1910,7 @@ int get_secret(ppp_pcb *pcb, const char *client, const char *server, char *secre
return 0;
}
len = (int)strlen(pcb->settings.passwd);
len = strlen(pcb->settings.passwd);
if (len > MAXSECRETLEN) {
ppp_error(("Secret for %s on %s is too long", client, server));
len = MAXSECRETLEN;
@ -1922,7 +1922,8 @@ int get_secret(ppp_pcb *pcb, const char *client, const char *server, char *secre
#if 0 /* UNUSED */
FILE *f;
int ret, len;
int ret;
size_t len;
char *filename;
struct wordlist *addrs, *opts;
char secbuf[MAXWORDLEN];