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commit 3bb748257405e94e13de76573a4e9da1cfd961d0
Author: Florian Weimer <fweimer@redhat.com>
Date: Tue Jul 3 15:54:49 2018 +0200
libio: Disable vtable validation in case of interposition [BZ #23313]
(cherry picked from commit c402355dfa7807b8e0adb27c009135a7e2b9f1b0)
Backported from the upstream release/2.27/master branch.
diff --git a/libio/vtables.c b/libio/vtables.c
index e364ea03edbfa75b..d6478e4bab9050ce 100644
--- a/libio/vtables.c
+++ b/libio/vtables.c
@@ -68,3 +68,19 @@ _IO_vtable_check (void)
__libc_fatal ("Fatal error: glibc detected an invalid stdio handle\n");
}
+
+/* Some variants of libstdc++ interpose _IO_2_1_stdin_ etc. and
+ install their own vtables directly, without calling _IO_init or
+ other functions. Detect this by looking at the vtables values
+ during startup, and disable vtable validation in this case. */
+#ifdef SHARED
+__attribute__ ((constructor))
+static void
+check_stdfiles_vtables (void)
+{
+ if (_IO_2_1_stdin_.vtable != &_IO_file_jumps
+ || _IO_2_1_stdout_.vtable != &_IO_file_jumps
+ || _IO_2_1_stderr_.vtable != &_IO_file_jumps)
+ IO_set_accept_foreign_vtables (&_IO_vtable_check);
+}
+#endif