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libio: Disable vtable validation in case of interposition [BZ #23313]

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Florian Weimer 2018-06-26 10:24:52 +02:00
parent 43b1048ab9
commit c402355dfa
2 changed files with 21 additions and 0 deletions
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ChangeLog
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@ -1,3 +1,8 @@
2018-06-26 Florian Weimer <fweimer@redhat.com>
[BZ #23313]
* libio/vtables.c (check_stdfiles_vtables): New ELF constructor.
2018-06-25 Florian Weimer <fweimer@redhat.com>
[BZ #18023]

16
libio/vtables.c
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@ -71,3 +71,19 @@ _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