d: Fix heap-buffer-overflow in checkModFileAlias [PR 99337]

The code wrongly assumed memcmp did not read past the mismatch.

gcc/d/ChangeLog:

	PR d/99337
	* dmd/dmodule.c (checkModFileAlias): Don't read past buffer in
	  comparison.

(cherry picked from commit d6177870dd2696501e3b8d3930fd5549d4acaeae)

diff --git a/gcc/d/dmd/dmodule.c b/gcc/d/dmd/dmodule.c
index bf1c0c1f0d901aa1d0ec4835f342a2e5f5b061db..c67626c00e59bb756029af28f94debcc426f31e1 100644 (file)
--- a/gcc/d/dmd/dmodule.c
+++ b/gcc/d/dmd/dmodule.c
@@ -202,7 +202,7 @@ static void checkModFileAlias(OutBuffer *buf, OutBuffer *dotmods,
         const char *m = (*ms)[j];
         const char *q = strchr(m, '=');
         assert(q);
-        if (dotmods->offset <= (size_t)(q - m) && memcmp(dotmods->peekString(), m, q - m) == 0)
+        if (dotmods->offset == (size_t)(q - m) && memcmp(dotmods->peekString(), m, q - m) == 0)
         {
             buf->reset();
             size_t qlen = strlen(q + 1);