Commit 5ef11c35 authored by Daniel Cashman's avatar Daniel Cashman Committed by Linus Torvalds
Browse files

mm: ASLR: use get_random_long() 



Replace calls to get_random_int() followed by a cast to (unsigned long)
with calls to get_random_long().  Also address shifting bug which, in
case of x86 removed entropy mask for mmap_rnd_bits values > 31 bits.

Signed-off-by: default avatarDaniel Cashman <dcashman@android.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nick Kralevich <nnk@google.com>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ec9ee4ac

arch/arm/mm/mmap.c

+1 −1
Original line number Diff line number Diff line
@@ -173,7 +173,7 @@ unsigned long arch_mmap_rnd(void) 
{

	unsigned long rnd;



	rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1);

	rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);



	return rnd << PAGE_SHIFT;

}

arch/arm64/mm/mmap.c

+2 −2
Original line number Diff line number Diff line
@@ -53,10 +53,10 @@ unsigned long arch_mmap_rnd(void) 


#ifdef CONFIG_COMPAT

	if (test_thread_flag(TIF_32BIT))

		rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_compat_bits) - 1);

		rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);

	else

#endif

		rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1);

		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);

	return rnd << PAGE_SHIFT;

}

arch/mips/mm/mmap.c

+2 −2
Original line number Diff line number Diff line
@@ -146,7 +146,7 @@ unsigned long arch_mmap_rnd(void) 
{

	unsigned long rnd;



	rnd = (unsigned long)get_random_int();

	rnd = get_random_long();

	rnd <<= PAGE_SHIFT;

	if (TASK_IS_32BIT_ADDR)

		rnd &= 0xfffffful;
@@ -174,7 +174,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) 


static inline unsigned long brk_rnd(void)

{

	unsigned long rnd = get_random_int();

	unsigned long rnd = get_random_long();



	rnd = rnd << PAGE_SHIFT;

	/* 8MB for 32bit, 256MB for 64bit */

arch/powerpc/kernel/process.c

+2 −2
Original line number Diff line number Diff line
@@ -1768,9 +1768,9 @@ static inline unsigned long brk_rnd(void) 


	/* 8MB for 32bit, 1GB for 64bit */

	if (is_32bit_task())

		rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT)));

		rnd = (get_random_long() % (1UL<<(23-PAGE_SHIFT)));

	else

		rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT)));

		rnd = (get_random_long() % (1UL<<(30-PAGE_SHIFT)));



	return rnd << PAGE_SHIFT;

}

arch/powerpc/mm/mmap.c

+2 −2
Original line number Diff line number Diff line
@@ -59,9 +59,9 @@ unsigned long arch_mmap_rnd(void) 


	/* 8MB for 32bit, 1GB for 64bit */

	if (is_32bit_task())

		rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT));

		rnd = get_random_long() % (1<<(23-PAGE_SHIFT));

	else

		rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT));

		rnd = get_random_long() % (1UL<<(30-PAGE_SHIFT));



	return rnd << PAGE_SHIFT;

}

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