linux-kernel - [tip:x86/urgent] x86/kasan: Flush TLBs after switching CR3

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Date:	Mon, 6 Jul 2015 08:37:04 -0700
From:	tip-bot for Andrey Ryabinin <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	adech.fo@...il.com, hpa@...or.com, dvyukov@...gle.com,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	peterz@...radead.org, tglx@...utronix.de, glider@...gle.com,
	a.ryabinin@...sung.com, bp@...en8.de, mingo@...nel.org,
	alpopov@...ecurity.com
Subject: [tip:x86/urgent] x86/kasan: Flush TLBs after switching CR3

Commit-ID:  241d2c54c62fa0939fc9a9512b48ac3434e90a89
Gitweb:     http://git.kernel.org/tip/241d2c54c62fa0939fc9a9512b48ac3434e90a89
Author:     Andrey Ryabinin <a.ryabinin@...sung.com>
AuthorDate: Thu, 2 Jul 2015 12:09:35 +0300
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 6 Jul 2015 14:53:14 +0200

x86/kasan: Flush TLBs after switching CR3

load_cr3() doesn't cause tlb_flush if PGE enabled.

This may cause tons of false positive reports spamming the
kernel to death.

To fix this __flush_tlb_all() should be called explicitly
after CR3 changed.

Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
Cc: <stable@...r.kernel.org> # 4.0+
Cc: Alexander Popov <alpopov@...ecurity.com>
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Andrey Konovalov <adech.fo@...il.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1435828178-10975-4-git-send-email-a.ryabinin@samsung.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/mm/kasan_init_64.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 0e4a05f..5d26642 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -208,6 +208,7 @@ void __init kasan_init(void)
 
 	memcpy(early_level4_pgt, init_level4_pgt, sizeof(early_level4_pgt));
 	load_cr3(early_level4_pgt);
+	__flush_tlb_all();
 
 	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 
@@ -234,5 +235,6 @@ void __init kasan_init(void)
 	memset(kasan_zero_page, 0, PAGE_SIZE);
 
 	load_cr3(init_level4_pgt);
+	__flush_tlb_all();
 	init_task.kasan_depth = 0;
 }
--
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