auth: pam - Allow at most 1024 messages from PAM

It is very unlikely that PAM would send more than this.

Co-Authored-By: netliomax25-code <netliomax25@gmail.com>

diff --git a/src/auth/passdb-pam.c b/src/auth/passdb-pam.c
index a4fb7aebf176ae7a8868bff00bdfe55f83f9b792..623034dea26529d6dab83a504c6de32ab7b361a0 100644 (file)
--- a/src/auth/passdb-pam.c
+++ b/src/auth/passdb-pam.c
@@ -32,6 +32,8 @@
 #  define pam_const const
 #endif
 
+#define PAM_MAX_MESSAGES 1024
+
 typedef pam_const void *pam_item_t;
 
 struct pam_passdb_module {
@@ -112,6 +114,12 @@ pam_userpass_conv(int num_msg, pam_const struct pam_message **msg,
        int i;
 
        *resp_r = NULL;
+       if (num_msg > PAM_MAX_MESSAGES) {
+               e_error(authdb_event(ctx->request),
+                       "PAM wanted to send %u messages, which exceeds limit %u",
+                       num_msg, PAM_MAX_MESSAGES);
+               return PAM_CONV_ERR;
+       }
 
        resp = calloc(num_msg, sizeof(struct pam_response));
        if (resp == NULL)