* [2.25 COMMITTED] libio: Disable vtable validation in case of interposition [BZ #23313]
@ 2019-01-01 0:00 Florian Weimer
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From: Florian Weimer @ 2019-01-01 0:00 UTC (permalink / raw)
To: libc-stable
(cherry picked from commit c402355dfa7807b8e0adb27c009135a7e2b9f1b0)
2018-06-26 Florian Weimer <fweimer@redhat.com>
[BZ #23313]
* libio/vtables.c (check_stdfiles_vtables): New ELF constructor.
diff --git a/libio/vtables.c b/libio/vtables.c
index 41b48db98c..a11226ab17 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);
+}
+#endif
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2019-01-01 0:00 [2.25 COMMITTED] libio: Disable vtable validation in case of interposition [BZ #23313] Florian Weimer
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