From: Yann Droneaud Date: Mon, 17 Nov 2014 23:02:19 +0000 (+0000) Subject: arm64/mm: Remove hack in mmap randomize layout X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=7dff766b1112c63e4a61ef797fd41aacef007bf4;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git arm64/mm: Remove hack in mmap randomize layout commit d6c763afab142a85e4770b4bc2a5f40f256d5c5d upstream. Since commit 8a0a9bd4db63 ('random: make get_random_int() more random'), get_random_int() returns a random value for each call, so comment and hack introduced in mmap_rnd() as part of commit 1d18c47c735e ('arm64: MMU fault handling and page table management') are incorrects. Commit 1d18c47c735e seems to use the same hack introduced by commit a5adc91a4b44 ('powerpc: Ensure random space between stack and mmaps'), latter copied in commit 5a0efea09f42 ('sparc64: Sharpen address space randomization calculations.'). But both architectures were cleaned up as part of commit fa8cbaaf5a68 ('powerpc+sparc64/mm: Remove hack in mmap randomize layout') as hack is no more needed since commit 8a0a9bd4db63. So the present patch removes the comment and the hack around get_random_int() on AArch64's mmap_rnd(). Cc: David S. Miller Cc: Anton Blanchard Cc: Benjamin Herrenschmidt Acked-by: Will Deacon Acked-by: Dan McGee Signed-off-by: Yann Droneaud Signed-off-by: Will Deacon Cc: Matthias Brugger Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index 83c3df2cb16..1bb487528a7 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -54,11 +54,12 @@ static unsigned long mmap_rnd(void) if (current->flags & PF_RANDOMIZE) { #ifdef CONFIG_COMPAT if (test_thread_flag(TIF_32BIT)) - rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); + rnd = get_random_long() & (1UL << mmap_rnd_compat_bits); else #endif - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); + rnd = get_random_long() & (1UL << mmap_rnd_bits); } + return rnd << PAGE_SHIFT; }