Re: [PATCH v6 4/4] x86: mm: support ARCH_MMAP_RND_BITS.

2015-12-14 Thread Daniel Cashman
On 12/14/2015 10:58 AM, H. Peter Anvin wrote: > On 12/11/15 09:52, Daniel Cashman wrote: >> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c >> index 844b06d..647fecf 100644 >> --- a/arch/x86/mm/mmap.c >> +++ b/arch/x86/mm/mmap.c >> @@ -69,14 +69,14 @@ unsigned long arch_mmap_rnd(void) >> {

Re: [PATCH v6 4/4] x86: mm: support ARCH_MMAP_RND_BITS.

2015-12-14 Thread H. Peter Anvin
On 12/11/15 09:52, Daniel Cashman wrote: > From: dcashman > > x86: arch_mmap_rnd() uses hard-coded values, 8 for 32-bit and 28 for > 64-bit, to generate the random offset for the mmap base address. > This value represents a compromise between increased ASLR > effectiveness and avoiding

Re: [PATCH v6 4/4] x86: mm: support ARCH_MMAP_RND_BITS.

2015-12-14 Thread H. Peter Anvin
On 12/11/15 09:52, Daniel Cashman wrote: > From: dcashman > > x86: arch_mmap_rnd() uses hard-coded values, 8 for 32-bit and 28 for > 64-bit, to generate the random offset for the mmap base address. > This value represents a compromise between increased ASLR > effectiveness

Re: [PATCH v6 4/4] x86: mm: support ARCH_MMAP_RND_BITS.

2015-12-14 Thread Daniel Cashman
On 12/14/2015 10:58 AM, H. Peter Anvin wrote: > On 12/11/15 09:52, Daniel Cashman wrote: >> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c >> index 844b06d..647fecf 100644 >> --- a/arch/x86/mm/mmap.c >> +++ b/arch/x86/mm/mmap.c >> @@ -69,14 +69,14 @@ unsigned long arch_mmap_rnd(void) >> {

[PATCH v6 4/4] x86: mm: support ARCH_MMAP_RND_BITS.

2015-12-11 Thread Daniel Cashman
From: dcashman x86: arch_mmap_rnd() uses hard-coded values, 8 for 32-bit and 28 for 64-bit, to generate the random offset for the mmap base address. This value represents a compromise between increased ASLR effectiveness and avoiding address-space fragmentation. Replace it with a Kconfig option,

[PATCH v6 4/4] x86: mm: support ARCH_MMAP_RND_BITS.

2015-12-11 Thread Daniel Cashman
From: dcashman x86: arch_mmap_rnd() uses hard-coded values, 8 for 32-bit and 28 for 64-bit, to generate the random offset for the mmap base address. This value represents a compromise between increased ASLR effectiveness and avoiding address-space fragmentation. Replace it