[vlc-commits] commit: config_PutPsz: fix potential use-after-free ( Rémi Denis-Courmont )

[git at videolan.org]

vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Sat May 29 18:25:36 2010 +0300| [6b35f6ff09419006d8af86cfb507fc644669a118] | committer: Rémi Denis-Courmont 

config_PutPsz: fix potential use-after-free

The new config value is duplicated, and the copy is stored to the
configuration. After the configuration R/W lock is released, we have no
warranty that another thread does not change the same configuration
item, and free our own copy. Admittedly, this is very unlikely.

Instead, we can simply pass the original string from the caller to the
callback - that one must remain valid through the config_PutPsz()
function call by definition.

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=6b35f6ff09419006d8af86cfb507fc644669a118
---

 src/config/core.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/config/core.c b/src/config/core.c
index 24925ef..b32577c 100644
--- a/src/config/core.c
+++ b/src/config/core.c
@@ -253,7 +253,7 @@ void config_PutPsz( vlc_object_t *p_this,
                       const char *psz_name, const char *psz_value )
 {
     module_config_t *p_config;
-    vlc_value_t oldval, val;
+    vlc_value_t oldval;
 
     p_config = config_FindConfig( p_this, psz_name );
 
@@ -283,13 +283,13 @@ void config_PutPsz( vlc_object_t *p_this,
 
     p_config->value.psz = str;
     p_config->b_dirty = true;
-
-    val.psz_string = (char *)p_config->value.psz;
-
     vlc_rwlock_unlock (&config_lock);
 
     if( p_config->pf_callback )
     {
+        vlc_value_t val;
+
+        val.psz_string = (char *)psz_value;
         p_config->pf_callback( p_this, psz_name, oldval, val,
                                p_config->p_callback_data );
     }