pppd: Don't try to free(NULL - 1)

A logic bug in update_script_environment() means that it can call
remove_script_env() even when the variable being removed is not
present in the script_env array.  The result of that is that
remove_script_env() will call free() with argument NULL - 1.
To fix this, we avoid calling remove_script_env() in this case.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/pppd/main.c b/pppd/main.c
index 76b67d2..e09b6ff 100644
--- a/pppd/main.c
+++ b/pppd/main.c
@@ -1751,7 +1751,7 @@ update_script_environment()
 		script_env[i] = newstring;
 	    else
 		add_script_env(i, newstring);
-	} else {
+	} else if (p != NULL) {
 	    remove_script_env(i);
 	}
     }