[Mesa-dev] [PATCH] egl/glvnd: Fix a segfault in eglGetProcAddress.

[Kyle Brenneman]

If FindProcIndex in egldispatchstubs.c is called with a name that's less than
the first entry in the array, it would end up trying to store an index of -1 in
an unsigned integer, wrap around to 2^32, and then crash when it tries to look
that up.

Change FindProcIndex so that it uses bsearch(3) instead of implementing its own
binary search, like the GLX equivalent FindGLXFunction does.
---
 src/egl/main/egldispatchstubs.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/src/egl/main/egldispatchstubs.c b/src/egl/main/egldispatchstubs.c
index e02abd7..bfc3195 100644
--- a/src/egl/main/egldispatchstubs.c
+++ b/src/egl/main/egldispatchstubs.c
@@ -2,6 +2,7 @@
 #include "g_egldispatchstubs.h"
 
 #include <string.h>
+#include <stdlib.h>
 
 #include "eglcurrent.h"
 
@@ -10,26 +11,21 @@ static const __EGLapiExports *exports;
 const int __EGL_DISPATCH_FUNC_COUNT = __EGL_DISPATCH_COUNT;
 int __EGL_DISPATCH_FUNC_INDICES[__EGL_DISPATCH_COUNT + 1];
 
+static int Compare(const void *l, const void *r)
+{
+    const char *s = *(const char **)r;
+    return strcmp(l, s);
+}
+
 static int FindProcIndex(const char *name)
 {
-    unsigned first = 0;
-    unsigned last = __EGL_DISPATCH_COUNT - 1;
-
-    while (first <= last) {
-        unsigned middle = (first + last) / 2;
-        int comp = strcmp(name,
-                          __EGL_DISPATCH_FUNC_NAMES[middle]);
-
-        if (comp > 0)
-            first = middle + 1;
-        else if (comp < 0)
-            last = middle - 1;
-        else
-            return middle;
-    }
+    const char **match = bsearch(name, __EGL_DISPATCH_FUNC_NAMES,
+            __EGL_DISPATCH_COUNT, sizeof(const char *), Compare);
+
+    if (match == NULL)
+        return __EGL_DISPATCH_COUNT;
 
-    /* Just point to the dummy entry at the end of the respective table */
-    return __EGL_DISPATCH_COUNT;
+    return match - __EGL_DISPATCH_FUNC_NAMES;
 }
 
 void __eglInitDispatchStubs(const __EGLapiExports *exportsTable)
-- 
2.7.4