Mesa (master): mesa: Prevent buffer underrun when handling MESA_GL_EXTENSION_OVERRIDE.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 3362c7d9b61462855f1e7d67da5d255de1b6ee7e
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=3362c7d9b61462855f1e7d67da5d255de1b6ee7e

Author: Eric Anholt <eric at anholt.net>
Date:   Mon Apr 23 17:12:04 2012 -0700

mesa: Prevent buffer underrun when handling MESA_GL_EXTENSION_OVERRIDE.

---

 src/mesa/main/extensions.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/mesa/main/extensions.c b/src/mesa/main/extensions.c
index 5f2c74a..a843a40 100644
--- a/src/mesa/main/extensions.c
+++ b/src/mesa/main/extensions.c
@@ -754,7 +754,7 @@ get_extension_override( struct gl_context *ctx )
 
    /* Remove trailing space. */
    len = strlen(extra_exts);
-   if (extra_exts[len - 1] == ' ')
+   if (len > 0 && extra_exts[len - 1] == ' ')
       extra_exts[len - 1] = '\0';
 
    return extra_exts;