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x86: use simpler API for random address requests 

Currently, all callers to randomize_range() set the length to 0 and
calculate end by adding a constant to the start address.  We can simplify
the API to remove a bunch of needless checks and variables.

Use the new randomize_addr(start, range) call to set the requested
address.

Link: http://lkml.kernel.org/r/20160803233913.32511-3-jason@lakedaemon.net
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jason Cooper 2016-10-11 13:53:56 -07:00 committed by Linus Torvalds
parent 99fdafdeac
commit 9c6f0902a5
2 changed files with 2 additions and 6 deletions
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3
arch/x86/kernel/process.c
View File

@ -509,8 +509,7 @@ unsigned long arch_align_stack(unsigned long sp)
unsigned long arch_randomize_brk(struct mm_struct *mm)
{
unsigned long range_end = mm->brk + 0x02000000;
return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
return randomize_page(mm->brk, 0x02000000);
}
/*

5
arch/x86/kernel/sys_x86_64.c
View File

@ -101,7 +101,6 @@ static void find_start_end(unsigned long flags, unsigned long *begin,
unsigned long *end)
{
if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) {
unsigned long new_begin;
/* This is usually used needed to map code in small
model, so it needs to be in the first 31bit. Limit
it to that. This means we need to move the
@ -112,9 +111,7 @@ static void find_start_end(unsigned long flags, unsigned long *begin,
*begin = 0x40000000;
*end = 0x80000000;
if (current->flags & PF_RANDOMIZE) {
new_begin = randomize_range(*begin, *begin + 0x02000000, 0);
if (new_begin)
*begin = new_begin;
*begin = randomize_page(*begin, 0x02000000);
}
} else {
*begin = current->mm->mmap_legacy_base;