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* [PATCH] x86/microcode/intel: Fix initrd loading with CONFIG_RANDOMIZE_MEMORY
@ 2016-07-26  9:51 Borislav Petkov
  2016-07-26 17:37 ` [tip:x86/microcode] x86/microcode/intel: Fix initrd loading with CONFIG_RANDOMIZE_MEMORY=y tip-bot for Borislav Petkov
  0 siblings, 1 reply; 11+ messages in thread
From: Borislav Petkov @ 2016-07-26  9:51 UTC (permalink / raw)
  To: X86 ML; +Cc: LKML, Borislav Petkov, Kees Cook

From: Borislav Petkov <bp@suse.de>

CONFIG_RANDOMIZE_MEMORY randomizes the physical memmap and thus the
address where the initrd is located. Therefore, we need to add the
offset KASLR put us to in order to find the initrd again on the AP path.

In the future, we will get rid of the initrd address caching and query
the address on both the BSP and AP paths but that would need more work.

Thanks to Nicolai Stange for the good bisection and debugging work.

Reported-and-tested-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>
---
 arch/x86/kernel/cpu/microcode/intel.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 6515c802346a..c5a7d74a9fa6 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -793,10 +793,10 @@ void __init load_ucode_intel_bsp(void)
 void load_ucode_intel_ap(void)
 {
 	struct ucode_blobs *blobs_p;
+	unsigned long *ptrs, start = 0;
 	struct mc_saved_data *mcs;
 	struct ucode_cpu_info uci;
 	enum ucode_state ret;
-	unsigned long *ptrs;
 
 #ifdef CONFIG_X86_32
 	mcs	= (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
@@ -815,8 +815,20 @@ void load_ucode_intel_ap(void)
 	if (!mcs->num_saved)
 		return;
 
+	if (blobs_p->valid) {
+		start = blobs_p->start;
+
+#ifdef CONFIG_RANDOMIZE_MEMORY
+		/*
+		 * Pay attention to CONFIG_RANDOMIZE_MEMORY as it shuffles
+		 * physmem mapping too and there we have the initrd.
+		 */
+		start += (PAGE_OFFSET - __PAGE_OFFSET_BASE);
+#endif
+	}
+
 	collect_cpu_info_early(&uci);
-	ret = load_microcode(mcs, ptrs, blobs_p->start, &uci);
+	ret = load_microcode(mcs, ptrs, start, &uci);
 	if (ret != UCODE_OK)
 		return;
 
-- 
2.8.4

^ permalink raw reply related	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2016-07-27 17:10 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-07-26  9:51 [PATCH] x86/microcode/intel: Fix initrd loading with CONFIG_RANDOMIZE_MEMORY Borislav Petkov
2016-07-26 17:37 ` [tip:x86/microcode] x86/microcode/intel: Fix initrd loading with CONFIG_RANDOMIZE_MEMORY=y tip-bot for Borislav Petkov
2016-07-26 20:37   ` Kees Cook
2016-07-27  5:45     ` Borislav Petkov
2016-07-27  8:09       ` [PATCH -v2 1/2] x86/asm: Add __PAGE_OFFSET_BASE define on 32-bit Borislav Petkov
2016-07-27  9:05         ` Ingo Molnar
2016-07-27  9:10           ` Borislav Petkov
2016-07-27 10:36             ` Ingo Molnar
2016-07-27 12:09               ` [PATCH] x86/asm, microcode: " Borislav Petkov
2016-07-27 17:10                 ` [tip:x86/microcode] x86/asm, x86/microcode: " tip-bot for Borislav Petkov
2016-07-27  8:11       ` [PATCH -v2 2/2] x86/microcode/intel: Fix initrd loading with CONFIG_RANDOMIZE_MEMORY Borislav Petkov

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