[2.32 COMMITTED 1/5] aarch64: Fix missing BTI protection from dependencies [BZ #26926]

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

The _dl_open_check and _rtld_main_check hooks are not called on the
dependencies of a loaded module, so BTI protection was missed on
every module other than the main executable and directly dlopened
libraries.

The fix just iterates over dependencies to enable BTI.

Fixes bug 26926.

(cherry picked from commit 72739c79f61989a76b7dd719f34fcfb7b8eadde9)
---
 sysdeps/aarch64/dl-bti.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/sysdeps/aarch64/dl-bti.c b/sysdeps/aarch64/dl-bti.c
index 196e462520..56c097210a 100644
--- a/sysdeps/aarch64/dl-bti.c
+++ b/sysdeps/aarch64/dl-bti.c
@@ -51,11 +51,24 @@ enable_bti (struct link_map *map, const char *program)
   return 0;
 }
 
-/* Enable BTI for L if required.  */
+/* Enable BTI for L and its dependencies.  */
 
 void
 _dl_bti_check (struct link_map *l, const char *program)
 {
-  if (GLRO(dl_aarch64_cpu_features).bti && l->l_mach.bti)
+  if (!GLRO(dl_aarch64_cpu_features).bti)
+    return;
+
+  if (l->l_mach.bti)
     enable_bti (l, program);
+
+  unsigned int i = l->l_searchlist.r_nlist;
+  while (i-- > 0)
+    {
+      struct link_map *dep = l->l_initfini[i];
+      if (dep->l_init_called)
+	continue;
+      if (dep->l_mach.bti)
+	enable_bti (dep, program);
+    }
 }
-- 
2.17.1