Re: [tip:x86/boot] x86/mm: Enable KASLR for physical mapping memory regions

[Borislav Petkov]

On Tue, Aug 16, 2016 at 03:49:28PM +0200, Borislav Petkov wrote:
> Just a stab in the dark: does something like that help?
> 
> ---
> diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
> index 27a0228c9cae..2debaf119baf 100644
> --- a/arch/x86/kernel/cpu/microcode/amd.c
> +++ b/arch/x86/kernel/cpu/microcode/amd.c
> @@ -434,6 +434,10 @@ int __init save_microcode_in_initrd_amd(void)
>  	else
>  		container = cont_va;
>  
> +#ifdef CONFIG_RANDOMIZE_MEMORY
> +	container += PAGE_OFFSET - __PAGE_OFFSET_BASE;
> +#endif
> +
>  	eax   = cpuid_eax(0x00000001);
>  	eax   = ((eax >> 8) & 0xf) + ((eax >> 20) & 0xff);
>  
> ---

Ok, I ran this in a guest and it finds the microcode patches properly.

My .config has:

CONFIG_ARCH_HAS_ELF_RANDOMIZE=y
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOMIZE_MEMORY=y
CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING=0x0

When you run this, please check whether it really applies the microcode
on every core.

Thanks.

Without the above, I get:

[    0.432103] BUG: unable to handle kernel paging request at ffff88007fa5540c
[    0.436000] IP: [<ffffffffbc03ea8b>] load_microcode_amd+0x2b/0x3b0
[    0.436000] PGD 0 
[    0.436000] Oops: 0000 [#1] PREEMPT SMP
[    0.436000] Modules linked in:
[    0.436000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-rc1+ #16
[    0.436000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[    0.436000] task: ffff9ebf7b460000 task.stack: ffff9ebf7bffc000
[    0.436000] RIP: 0010:[<ffffffffbc03ea8b>]  [<ffffffffbc03ea8b>] load_microcode_amd+0x2b/0x3b0
[    0.436000] RSP: 0018:ffff9ebf7bfffe08  EFLAGS: 00010246
[    0.436000] RAX: 0000000080000000 RBX: 0000000000000006 RCX: 0000000000001ec4
[    0.436000] RDX: ffff88007fa55408 RSI: 0000000000000015 RDI: 0000000000000000
[    0.436000] RBP: ffff9ebf7bfffe48 R08: ffff9ebf7b805960 R09: 0000000000000000
[    0.436000] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000001ec4
[    0.436000] R13: ffff88007fa55408 R14: 0000000000000015 R15: 0000000000001ec4
[    0.436000] FS:  0000000000000000(0000) GS:ffff9ebf7e800000(0000) knlGS:0000000000000000
[    0.436000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.436000] CR2: ffff88007fa5540c CR3: 0000000067c06000 CR4: 00000000000406f0
[    0.436000] Stack:
[    0.436000]  ffff9ebf7b805900 0000000000000246 0000000000000006 0000000000000006
[    0.436000]  0000000000000000 000000000000000f ffff88007fa55408 0000000000001ec4
[    0.436000]  ffff9ebf7bfffe80 ffffffffbcd49762 0000000000000000 00000000000000ee
[    0.436000] Call Trace:
[    0.436000]  [<ffffffffbcd49762>] save_microcode_in_initrd_amd+0xac/0xe0
[    0.436000]  [<ffffffffbcd49037>] ? microcode_init+0x1b1/0x1b1
[    0.436000]  [<ffffffffbcd49073>] save_microcode_in_initrd+0x3c/0x45
[    0.436000]  [<ffffffffbc000459>] do_one_initcall+0x59/0x190
[    0.436000]  [<ffffffffbc08ccc1>] ? parse_args+0x271/0x400
[    0.436000]  [<ffffffffbcd3d089>] kernel_init_freeable+0x118/0x19e
[    0.436000]  [<ffffffffbc76aa3e>] kernel_init+0xe/0x100
[    0.436000]  [<ffffffffbc7749ef>] ret_from_fork+0x1f/0x40
[    0.436000]  [<ffffffffbc76aa30>] ? rest_init+0x140/0x140
[    0.436000] Code: 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 89 f6 41 55 49 89 d5 41 54 49 89 cc 53 48 83 ec 18 48 8b 3d d2 d9 e2 00 e8 e5 15 18 00 <41> 8b 4d 04 48 c7 05 be d9 e2 00 00 00 00 00 41 8b 5d 08 85 c9 
[    0.436000] RIP  [<ffffffffbc03ea8b>] load_microcode_amd+0x2b/0x3b0
[    0.436000]  RSP <ffff9ebf7bfffe08>
[    0.436000] CR2: ffff88007fa5540c
[    0.436000] ---[ end trace 21a612b6619d1c00 ]---
[    0.436019] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009
[    0.436019] 
[    0.438843] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009
[    0.438843]

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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