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* [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly
@ 2022-04-03 13:49 Christophe Leroy
  2022-04-04  7:49 ` Greg KH
  0 siblings, 1 reply; 7+ messages in thread
From: Christophe Leroy @ 2022-04-03 13:49 UTC (permalink / raw)
  To: gregkh, stable
  Cc: Christophe Leroy, linux-kernel, linuxppc-dev, Chen Jingwen,
	Michael Ellerman

From: Chen Jingwen <chenjingwen6@huawei.com>

This is backport for 5.4

Upstream commit dd75080aa8409ce10d50fb58981c6b59bf8707d3

The shadow's page table is not updated when PTE_RPN_SHIFT is 24
and PAGE_SHIFT is 12. It not only causes false positives but
also false negative as shown the following text.

Fix it by bringing the logic of kasan_early_shadow_page_entry here.

1. False Positive:
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50
Write of size 16 at addr f57f3be0 by task swapper/0/1

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1
Call Trace:
[c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable)
[c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300
[c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200
[c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0
[c80d1cc0] [c03018a4] memset+0x34/0x90
[c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50
[c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570
[c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0
[c80d1db0] [c2036580] init_sd+0xc4/0x1d0
[c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c
[c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384
[c80d1ef0] [c0004b14] kernel_init+0x24/0x170
[c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64

Memory state around the buggy address:
 f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                               ^
 f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

2. False Negative (with KASAN tests):
==================================================================
Before fix:
    ok 45 - kmalloc_double_kzfree
    # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039
    KASAN failure expected in "((volatile char *)area)[3100]", but none occurred
    not ok 46 - vmalloc_oob
    not ok 1 - kasan

==================================================================
After fix:
    ok 1 - kasan

Fixes: cbd18991e24fe ("powerpc/mm: Fix an Oops in kasan_mmu_init()")
Cc: stable@vger.kernel.org # 5.4.x
Signed-off-by: Chen Jingwen <chenjingwen6@huawei.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211229035226.59159-1-chenjingwen6@huawei.com
[chleroy: Backport for 5.4]
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/kasan/kasan_init_32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index 1cfe57b51d7e..3f78007a7282 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -121,7 +121,7 @@ static void __init kasan_remap_early_shadow_ro(void)
 		pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
 		pte_t *ptep = pte_offset_kernel(pmd, k_cur);
 
-		if ((pte_val(*ptep) & PTE_RPN_MASK) != pa)
+		if (pte_page(*ptep) != virt_to_page(lm_alias(kasan_early_shadow_page)))
 			continue;
 
 		__set_pte_at(&init_mm, k_cur, ptep, pfn_pte(PHYS_PFN(pa), prot), 0);
-- 
2.35.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread
* Re: [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly
  2022-04-03 13:49 [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly Christophe Leroy
@ 2022-04-04  7:49 ` Greg KH
  0 siblings, 0 replies; 7+ messages in thread
From: Greg KH @ 2022-04-04  7:49 UTC (permalink / raw)
  To: Christophe Leroy
  Cc: stable, linux-kernel, linuxppc-dev, Chen Jingwen, Michael Ellerman

On Sun, Apr 03, 2022 at 03:49:43PM +0200, Christophe Leroy wrote:
> From: Chen Jingwen <chenjingwen6@huawei.com>
> 
> This is backport for 5.4
> 
> Upstream commit dd75080aa8409ce10d50fb58981c6b59bf8707d3

Now queued up, thanks.

greg k-h

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly
  2022-04-02 16:13 Christophe Leroy
  2022-04-03 10:25 ` Greg KH
@ 2022-04-12  2:17 ` ChenJingwen
  1 sibling, 0 replies; 7+ messages in thread
From: ChenJingwen @ 2022-04-12  2:17 UTC (permalink / raw)
  To: christophe.leroy
  Cc: chenjingwen6, gregkh, linux-kernel, linuxppc-dev, mpe, stable

> This is backport for 5.4
> 
> Upstream commit 5647a94a26e352beed61788b46e035d9d12664cd

Thank you for your rebase.
I went on vacation and couldn't submit the code at that time

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly
  2022-04-03 11:54   ` Christophe Leroy
@ 2022-04-03 12:26     ` Greg KH
  0 siblings, 0 replies; 7+ messages in thread
From: Greg KH @ 2022-04-03 12:26 UTC (permalink / raw)
  To: Christophe Leroy
  Cc: stable, linux-kernel, linuxppc-dev, Chen Jingwen, Michael Ellerman

On Sun, Apr 03, 2022 at 11:54:55AM +0000, Christophe Leroy wrote:
> 
> 
> Le 03/04/2022 à 12:25, Greg KH a écrit :
> > On Sat, Apr 02, 2022 at 06:13:31PM +0200, Christophe Leroy wrote:
> >> From: Chen Jingwen <chenjingwen6@huawei.com>
> >>
> >> This is backport for 5.4
> >>
> >> Upstream commit 5647a94a26e352beed61788b46e035d9d12664cd
> > 
> > This is not a commit in Linus's tree :(
> > 
> 
> Oops. Don't know what I did, that's indeed the commit after I 
> cherry-picked it on top of 5.4.188 and before I modified it.
> 
> According to the mail you sent me yesterday to tell it FAILED to apply 
> on 5.4, the upstream commit is dd75080aa8409ce10d50fb58981c6b59bf8707d3

Can you resend with this fixed up please?

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly
  2022-04-03 10:25 ` Greg KH
@ 2022-04-03 11:54   ` Christophe Leroy
  2022-04-03 12:26     ` Greg KH
  0 siblings, 1 reply; 7+ messages in thread
From: Christophe Leroy @ 2022-04-03 11:54 UTC (permalink / raw)
  To: Greg KH
  Cc: stable, linux-kernel, linuxppc-dev, Chen Jingwen, Michael Ellerman



Le 03/04/2022 à 12:25, Greg KH a écrit :
> On Sat, Apr 02, 2022 at 06:13:31PM +0200, Christophe Leroy wrote:
>> From: Chen Jingwen <chenjingwen6@huawei.com>
>>
>> This is backport for 5.4
>>
>> Upstream commit 5647a94a26e352beed61788b46e035d9d12664cd
> 
> This is not a commit in Linus's tree :(
> 

Oops. Don't know what I did, that's indeed the commit after I 
cherry-picked it on top of 5.4.188 and before I modified it.

According to the mail you sent me yesterday to tell it FAILED to apply 
on 5.4, the upstream commit is dd75080aa8409ce10d50fb58981c6b59bf8707d3

Thanks
Christophe

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly
  2022-04-02 16:13 Christophe Leroy
@ 2022-04-03 10:25 ` Greg KH
  2022-04-03 11:54   ` Christophe Leroy
  2022-04-12  2:17 ` ChenJingwen
  1 sibling, 1 reply; 7+ messages in thread
From: Greg KH @ 2022-04-03 10:25 UTC (permalink / raw)
  To: Christophe Leroy
  Cc: stable, linux-kernel, linuxppc-dev, Chen Jingwen, Michael Ellerman

On Sat, Apr 02, 2022 at 06:13:31PM +0200, Christophe Leroy wrote:
> From: Chen Jingwen <chenjingwen6@huawei.com>
> 
> This is backport for 5.4
> 
> Upstream commit 5647a94a26e352beed61788b46e035d9d12664cd

This is not a commit in Linus's tree :(


^ permalink raw reply	[flat|nested] 7+ messages in thread
* [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly
@ 2022-04-02 16:13 Christophe Leroy
  2022-04-03 10:25 ` Greg KH
  2022-04-12  2:17 ` ChenJingwen
  0 siblings, 2 replies; 7+ messages in thread
From: Christophe Leroy @ 2022-04-02 16:13 UTC (permalink / raw)
  To: gregkh, stable
  Cc: Christophe Leroy, linux-kernel, linuxppc-dev, Chen Jingwen,
	Michael Ellerman

From: Chen Jingwen <chenjingwen6@huawei.com>

This is backport for 5.4

Upstream commit 5647a94a26e352beed61788b46e035d9d12664cd

The shadow's page table is not updated when PTE_RPN_SHIFT is 24
and PAGE_SHIFT is 12. It not only causes false positives but
also false negative as shown the following text.

Fix it by bringing the logic of kasan_early_shadow_page_entry here.

1. False Positive:
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50
Write of size 16 at addr f57f3be0 by task swapper/0/1

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1
Call Trace:
[c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable)
[c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300
[c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200
[c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0
[c80d1cc0] [c03018a4] memset+0x34/0x90
[c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50
[c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570
[c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0
[c80d1db0] [c2036580] init_sd+0xc4/0x1d0
[c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c
[c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384
[c80d1ef0] [c0004b14] kernel_init+0x24/0x170
[c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64

Memory state around the buggy address:
 f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                               ^
 f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

2. False Negative (with KASAN tests):
==================================================================
Before fix:
    ok 45 - kmalloc_double_kzfree
    # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039
    KASAN failure expected in "((volatile char *)area)[3100]", but none occurred
    not ok 46 - vmalloc_oob
    not ok 1 - kasan

==================================================================
After fix:
    ok 1 - kasan

Fixes: cbd18991e24fe ("powerpc/mm: Fix an Oops in kasan_mmu_init()")
Cc: stable@vger.kernel.org # 5.4.x
Signed-off-by: Chen Jingwen <chenjingwen6@huawei.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211229035226.59159-1-chenjingwen6@huawei.com
[chleroy: Backport for 5.4]
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/kasan/kasan_init_32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index 1cfe57b51d7e..3f78007a7282 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -121,7 +121,7 @@ static void __init kasan_remap_early_shadow_ro(void)
 		pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
 		pte_t *ptep = pte_offset_kernel(pmd, k_cur);
 
-		if ((pte_val(*ptep) & PTE_RPN_MASK) != pa)
+		if (pte_page(*ptep) != virt_to_page(lm_alias(kasan_early_shadow_page)))
 			continue;
 
 		__set_pte_at(&init_mm, k_cur, ptep, pfn_pte(PHYS_PFN(pa), prot), 0);
-- 
2.35.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-04-12  2:17 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2022-04-03 13:49 [PATCH] [Rebased for 5.4] powerpc/kasan: Fix early region not updated correctly Christophe Leroy
2022-04-04  7:49 ` Greg KH
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2022-04-02 16:13 Christophe Leroy
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