From 9e800c2928358cc9060eaa4f17b8f0a3a1269d65 Mon Sep 17 00:00:00 2001
From: "Dmitry V. Levin" <ldv@altlinux.org>
Date: Wed, 23 Feb 2022 08:00:00 +0000
Subject: pam_exec: remove redundant free() invocations

In the child process, freeing memory right before pam_syslog()
followed by _exit(ENOMEM) is useless.

* modules/pam_exec/pam_exec.c (call_exec): Do not call free(envlist).

Resolves: https://github.com/linux-pam/linux-pam/issues/444
---
 modules/pam_exec/pam_exec.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

(limited to 'modules/pam_exec')

diff --git a/modules/pam_exec/pam_exec.c b/modules/pam_exec/pam_exec.c
index 3fd388a5..23cc0bac 100644
--- a/modules/pam_exec/pam_exec.c
+++ b/modules/pam_exec/pam_exec.c
@@ -307,7 +307,7 @@ call_exec (const char *pam_type, pam_handle_t *pamh,
     {
       const char **arggv;
       int i;
-      char **envlist, **tmp;
+      char **envlist;
       int envlen, nitems;
       char *envstr;
       enum pam_modutil_redirect_fd redirect_stdin =
@@ -430,14 +430,12 @@ call_exec (const char *pam_type, pam_handle_t *pamh,
         /* nothing */ ;
       nitems = PAM_ARRAY_SIZE(env_items);
       /* + 2 because of PAM_TYPE and NULL entry */
-      tmp = realloc(envlist, (envlen + nitems + 2) * sizeof(*envlist));
-      if (tmp == NULL)
+      envlist = realloc(envlist, (envlen + nitems + 2) * sizeof(*envlist));
+      if (envlist == NULL)
       {
-        free(envlist);
         pam_syslog (pamh, LOG_CRIT, "realloc environment failed: %m");
         _exit (ENOMEM);
       }
-      envlist = tmp;
       for (i = 0; i < nitems; ++i)
       {
         const void *item;
@@ -446,7 +444,6 @@ call_exec (const char *pam_type, pam_handle_t *pamh,
           continue;
         if (asprintf(&envstr, "%s=%s", env_items[i].name, (const char *)item) < 0)
         {
-          free(envlist);
           pam_syslog (pamh, LOG_CRIT, "prepare environment failed: %m");
           _exit (ENOMEM);
         }
@@ -456,7 +453,6 @@ call_exec (const char *pam_type, pam_handle_t *pamh,
 
       if (asprintf(&envstr, "PAM_TYPE=%s", pam_type) < 0)
         {
-          free(envlist);
           pam_syslog (pamh, LOG_CRIT, "prepare environment failed: %m");
           _exit (ENOMEM);
         }
@@ -471,7 +467,6 @@ call_exec (const char *pam_type, pam_handle_t *pamh,
       DIAG_POP_IGNORE_CAST_QUAL;
       i = errno;
       pam_syslog (pamh, LOG_ERR, "execve(%s,...) failed: %m", arggv[0]);
-      free(envlist);
       _exit (i);
     }
   return PAM_SYSTEM_ERR; /* will never be reached. */
-- 
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