This is a note to let you know that I've just added the patch titled
x86/kasan: Write protect kasan zero shadow
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-kasan-write-protect-kasan-zero-shadow.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 063fb3e56f6dd29b2633b678b837e1d904200e6f Mon Sep 17 00:00:00 2001
From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Date: Mon, 11 Jan 2016 15:51:19 +0300
Subject: x86/kasan: Write protect kasan zero shadow
From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
commit 063fb3e56f6dd29b2633b678b837e1d904200e6f upstream.
After kasan_init() executed, no one is allowed to write to kasan_zero_page,
so write protect it.
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Luis R. Rodriguez <mcgrof@xxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxx>
Cc: linux-mm@xxxxxxxxx
Link: http://lkml.kernel.org/r/1452516679-32040-3-git-send-email-aryabinin@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/kasan_init_64.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -126,10 +126,16 @@ void __init kasan_init(void)
/*
* kasan_zero_page has been used as early shadow memory, thus it may
- * contain some garbage. Now we can clear it, since after the TLB flush
- * no one should write to it.
+ * contain some garbage. Now we can clear and write protect it, since
+ * after the TLB flush no one should write to it.
*/
memset(kasan_zero_page, 0, PAGE_SIZE);
+ for (i = 0; i < PTRS_PER_PTE; i++) {
+ pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO);
+ set_pte(&kasan_zero_pte[i], pte);
+ }
+ /* Flush TLBs again to be sure that write protection applied. */
+ __flush_tlb_all();
init_task.kasan_depth = 0;
pr_info("KernelAddressSanitizer initialized\n");
Patches currently in stable-queue which might be from aryabinin@xxxxxxxxxxxxx are
queue-4.4/x86-kasan-write-protect-kasan-zero-shadow.patch