mesa: fix a valgrind warning

==5715== Invalid read of size 4
==5715==    at 0x4AA590B: _mesa_make_extension_string (extensions.c:908)
==5715==    by 0x4A83198: _mesa_make_current (context.c:1514)
==5715==    by 0x4A71CAB: st_api_make_current (st_manager.c:789)
==5715==  Address 0x4795730 is 0 bytes inside a block of size 1 alloc'd
==5715==    at 0x4025315: calloc (vg_replace_malloc.c:467)
==5715==    by 0x4AA5B4C: _mesa_make_extension_string (extensions.c:772)
==5715==    by 0x4A83198: _mesa_make_current (context.c:1514)
==5715==    by 0x4A71CAB: st_api_make_current (st_manager.c:789)

diff --git a/src/mesa/main/extensions.c b/src/mesa/main/extensions.c
index 1903a503c0d3f507eca54541e8795ba6ab48b574..aceddaa3ef22627e97bc890335c6316addac65f8 100644 (file)
--- a/src/mesa/main/extensions.c
+++ b/src/mesa/main/extensions.c
@@ -769,7 +769,7 @@ get_extension_override( struct gl_context *ctx )
    if (env_const == NULL) {
       /* Return the empty string rather than NULL. This simplifies the logic
        * of client functions. */
-      return calloc(1, sizeof(char));
+      return calloc(4, sizeof(char));
    }
 
    /* extra_exts: List of unrecognized extensions. */