[Bug driver/89014] Use-after-free in aarch64 -march=native

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89014

--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
The obvious fix:

diff --git a/gcc/config/aarch64/driver-aarch64.c
b/gcc/config/aarch64/driver-aarch64.c
index 2bf1f9a8c13..100e0c3529c 100644
--- a/gcc/config/aarch64/driver-aarch64.c
+++ b/gcc/config/aarch64/driver-aarch64.c
@@ -178,7 +178,6 @@ host_detect_local_cpu (int argc, const char **argv)
   unsigned int variants[2] = { ALL_VARIANTS, ALL_VARIANTS };
   unsigned int n_variants = 0;
   bool processed_exts = false;
-  const char *ext_string = "";
   unsigned long extension_flags = 0;
   unsigned long default_flags = 0;

@@ -348,11 +347,12 @@ host_detect_local_cpu (int argc, const char **argv)
   if (tune)
     return res;

-  ext_string
-    = aarch64_get_extension_string_for_isa_flags (extension_flags,
-                                                 default_flags).c_str ();
-
-  res = concat (res, ext_string, NULL);
+  {
+    std::string extension
+      = aarch64_get_extension_string_for_isa_flags (extension_flags,
+                                                   default_flags);
+    res = concat (res, extension.c_str (), NULL);
+  }

   return res;

fixes the valgrind error, but (on this box) leads to:

$ ./xgcc -B. -c test.c -march=native
Assembler messages:
Error: unknown architectural extension `rng+memtag+sb+ssbs+predres'
Error: unrecognized option -march=armv8-a+profile+rng+memtag+sb+ssbs+predres