From 0f780b1aebb1b1bde219401735a1c24c1f0a7978 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Mon, 26 Oct 2020 12:49:21 +0100
Subject: [PATCH] g10: Make call to agent_scd_serialno more robust.

* g10/call-agent.c (agent_scd_serialno): Make sure that NULL is stored
on error at r_serialno.
* g10/card-util.c (card_status): Simplify freeing of seriaono.
(factory_reset): Ditto.
--

This pattern is what we use with other functions returning an
allocated string and thus less surprising.
---
 g10/call-agent.c |  1 +
 g10/card-util.c  | 10 +++++-----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/g10/call-agent.c b/g10/call-agent.c
index 1fa77e7be..c4d146392 100644
--- a/g10/call-agent.c
+++ b/g10/call-agent.c
@@ -1381,6 +1381,7 @@ agent_scd_serialno (char **r_serialno, const char *demand)
   char *serialno = NULL;
   char line[ASSUAN_LINELENGTH];
 
+  *r_serialno = NULL;
   err = start_agent (NULL, (1 | FLAG_FOR_CARD_SUPPRESS_ERRORS));
   if (err)
     return err;
diff --git a/g10/card-util.c b/g10/card-util.c
index 168427552..d43081588 100644
--- a/g10/card-util.c
+++ b/g10/card-util.c
@@ -688,7 +688,8 @@ card_status (ctrl_t ctrl, estream_t fp, const char *serialno)
 {
   int err;
   strlist_t card_list, sl;
-  char *serialno0, *serialno1;
+  char *serialno0 = NULL;
+  char *serialno1 = NULL;
   int all_cards = 0;
   int any_card = 0;
 
@@ -733,6 +734,7 @@ card_status (ctrl_t ctrl, estream_t fp, const char *serialno)
 
       current_card_status (ctrl, fp, NULL, 0);
       xfree (serialno1);
+      serialno1 = NULL;
 
       if (!all_cards)
         goto leave;
@@ -740,11 +742,10 @@ card_status (ctrl_t ctrl, estream_t fp, const char *serialno)
 
   /* Select the original card again.  */
   err = agent_scd_serialno (&serialno1, serialno0);
-  if (!err)
-    xfree (serialno1);
 
  leave:
   xfree (serialno0);
+  xfree (serialno1);
   free_strlist (card_list);
 }
 
@@ -2000,8 +2001,7 @@ factory_reset (void)
       char *serialno0;
 
       err = agent_scd_serialno (&serialno0, NULL);
-      if (!err)
-        xfree (serialno0);
+      xfree (serialno0);
     }
 
  leave: