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From: Florian Weimer <>
Subject: [2.24 COMMITTED] libio: Disable vtable validation in case of interposition [BZ #23313]
Date: Tue, 01 Jan 2019 00:00:00 -0000	[thread overview]
Message-ID: <> (raw)

(cherry picked from commit c402355dfa7807b8e0adb27c009135a7e2b9f1b0)

2018-06-26  Florian Weimer  <>

	[BZ #23313]
	* libio/vtables.c (check_stdfiles_vtables): New ELF constructor.

diff --git a/libio/vtables.c b/libio/vtables.c
index b361f44e91..722a090790 100644
--- a/libio/vtables.c
+++ b/libio/vtables.c
@@ -70,3 +70,19 @@ _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);

                 reply	other threads:[~2019-11-28 16:48 UTC|newest]

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