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/* Stack executability handling for GNU dynamic linker. Linux version.
Copyright (C) 2003-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <ldsodefs.h>
#include <sys/mman.h>
#include <errno.h>
#include <libintl.h>
#include <stdbool.h>
#include <stackinfo.h>
#include <caller.h>
#include <sysdep.h>
extern int __stack_prot attribute_relro attribute_hidden;
int
internal_function
_dl_make_stack_executable (void **stack_endp)
{
/* This gives us the highest/lowest page that needs to be changed. */
uintptr_t page = ((uintptr_t) *stack_endp
& -(intptr_t) GLRO(dl_pagesize));
int result = 0;
/* Challenge the caller. */
if (__builtin_expect (__check_caller (RETURN_ADDRESS (0),
allow_ldso|allow_libpthread) != 0, 0)
|| __builtin_expect (*stack_endp != __libc_stack_end, 0))
return EPERM;
if (__builtin_expect (__mprotect ((void *) page, GLRO(dl_pagesize),
__stack_prot) == 0, 1))
goto return_success;
result = errno;
goto out;
return_success:
/* Clear the address. */
*stack_endp = NULL;
/* Remember that we changed the permission. */
GL(dl_stack_flags) |= PF_X;
out:
#ifdef check_consistency
check_consistency ();
#endif
return result;
}
rtld_hidden_def (_dl_make_stack_executable)
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