* [PATCH] mm: Fix NULL page->mapping dereference in page_is_secretmem()
@ 2021-10-07 23:15 Sean Christopherson
2021-10-08 10:46 ` David Hildenbrand
2021-10-10 5:29 ` Mike Rapoport
0 siblings, 2 replies; 4+ messages in thread
From: Sean Christopherson @ 2021-10-07 23:15 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-kernel, Mike Rapoport, linux-mm, Darrick J . Wong, Stephen,
Sean Christopherson
Check for a NULL page->mapping before dereferencing the mapping in
page_is_secretmem(), as the page's mapping can be nullified while gup()
is running, e.g. by reclaim or truncation.
BUG: kernel NULL pointer dereference, address: 0000000000000068
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 6 PID: 4173897 Comm: CPU 3/KVM Tainted: G W
RIP: 0010:internal_get_user_pages_fast+0x621/0x9d0
Code: <48> 81 7a 68 80 08 04 bc 0f 85 21 ff ff 8 89 c7 be
RSP: 0018:ffffaa90087679b0 EFLAGS: 00010046
RAX: ffffe3f37905b900 RBX: 00007f2dd561e000 RCX: ffffe3f37905b934
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe3f37905b900
...
CR2: 0000000000000068 CR3: 00000004c5898003 CR4: 00000000001726e0
Call Trace:
get_user_pages_fast_only+0x13/0x20
hva_to_pfn+0xa9/0x3e0
try_async_pf+0xa1/0x270
direct_page_fault+0x113/0xad0
kvm_mmu_page_fault+0x69/0x680
vmx_handle_exit+0xe1/0x5d0
kvm_arch_vcpu_ioctl_run+0xd81/0x1c70
kvm_vcpu_ioctl+0x267/0x670
__x64_sys_ioctl+0x83/0xa0
do_syscall_64+0x56/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Cc: Mike Rapoport <rppt@kernel.org>
Cc: linux-mm@kvack.org
Reported-by: Darrick J. Wong <djwong@kernel.org>
Reported-by: Stephen <stephenackerman16@gmail.com>
Tested-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
include/linux/secretmem.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
index 21c3771e6a56..988528b5da43 100644
--- a/include/linux/secretmem.h
+++ b/include/linux/secretmem.h
@@ -23,7 +23,7 @@ static inline bool page_is_secretmem(struct page *page)
mapping = (struct address_space *)
((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
- if (mapping != page->mapping)
+ if (!mapping || mapping != page->mapping)
return false;
return mapping->a_ops == &secretmem_aops;
--
2.33.0.882.g93a45727a2-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: Fix NULL page->mapping dereference in page_is_secretmem()
2021-10-07 23:15 [PATCH] mm: Fix NULL page->mapping dereference in page_is_secretmem() Sean Christopherson
@ 2021-10-08 10:46 ` David Hildenbrand
2021-10-08 14:17 ` Sean Christopherson
2021-10-10 5:29 ` Mike Rapoport
1 sibling, 1 reply; 4+ messages in thread
From: David Hildenbrand @ 2021-10-08 10:46 UTC (permalink / raw)
To: Sean Christopherson, Andrew Morton
Cc: linux-kernel, Mike Rapoport, linux-mm, Darrick J . Wong, Stephen
On 08.10.21 01:15, Sean Christopherson wrote:
> Check for a NULL page->mapping before dereferencing the mapping in
> page_is_secretmem(), as the page's mapping can be nullified while gup()
> is running, e.g. by reclaim or truncation.
>
> BUG: kernel NULL pointer dereference, address: 0000000000000068
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 0 P4D 0
> Oops: 0000 [#1] PREEMPT SMP NOPTI
> CPU: 6 PID: 4173897 Comm: CPU 3/KVM Tainted: G W
> RIP: 0010:internal_get_user_pages_fast+0x621/0x9d0
> Code: <48> 81 7a 68 80 08 04 bc 0f 85 21 ff ff 8 89 c7 be
> RSP: 0018:ffffaa90087679b0 EFLAGS: 00010046
> RAX: ffffe3f37905b900 RBX: 00007f2dd561e000 RCX: ffffe3f37905b934
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe3f37905b900
> ...
> CR2: 0000000000000068 CR3: 00000004c5898003 CR4: 00000000001726e0
> Call Trace:
> get_user_pages_fast_only+0x13/0x20
> hva_to_pfn+0xa9/0x3e0
> try_async_pf+0xa1/0x270
> direct_page_fault+0x113/0xad0
> kvm_mmu_page_fault+0x69/0x680
> vmx_handle_exit+0xe1/0x5d0
> kvm_arch_vcpu_ioctl_run+0xd81/0x1c70
> kvm_vcpu_ioctl+0x267/0x670
> __x64_sys_ioctl+0x83/0xa0
> do_syscall_64+0x56/0x80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: linux-mm@kvack.org
> Reported-by: Darrick J. Wong <djwong@kernel.org>
> Reported-by: Stephen <stephenackerman16@gmail.com>
> Tested-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> include/linux/secretmem.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
> index 21c3771e6a56..988528b5da43 100644
> --- a/include/linux/secretmem.h
> +++ b/include/linux/secretmem.h
> @@ -23,7 +23,7 @@ static inline bool page_is_secretmem(struct page *page)
> mapping = (struct address_space *)
> ((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
>
> - if (mapping != page->mapping)
> + if (!mapping || mapping != page->mapping)
> return false;
>
> return mapping->a_ops == &secretmem_aops;
>
I assume we want to add
Fixes: 1507f51255c9 ("mm: introduce memfd_secret system call to create "secret" memory areas")
Cc: <stable@vger.kernel.org> # v5.14
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mm: Fix NULL page->mapping dereference in page_is_secretmem()
2021-10-08 10:46 ` David Hildenbrand
@ 2021-10-08 14:17 ` Sean Christopherson
0 siblings, 0 replies; 4+ messages in thread
From: Sean Christopherson @ 2021-10-08 14:17 UTC (permalink / raw)
To: David Hildenbrand
Cc: Andrew Morton, linux-kernel, Mike Rapoport, linux-mm,
Darrick J . Wong, Stephen
On Fri, Oct 08, 2021, David Hildenbrand wrote:
> I assume we want to add
>
> Fixes: 1507f51255c9 ("mm: introduce memfd_secret system call to create "secret" memory areas")
> Cc: <stable@vger.kernel.org> # v5.14
Doh, yes we do. Thanks!
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: Fix NULL page->mapping dereference in page_is_secretmem()
2021-10-07 23:15 [PATCH] mm: Fix NULL page->mapping dereference in page_is_secretmem() Sean Christopherson
2021-10-08 10:46 ` David Hildenbrand
@ 2021-10-10 5:29 ` Mike Rapoport
1 sibling, 0 replies; 4+ messages in thread
From: Mike Rapoport @ 2021-10-10 5:29 UTC (permalink / raw)
To: Sean Christopherson
Cc: Andrew Morton, linux-kernel, linux-mm, Darrick J . Wong, Stephen
On Thu, Oct 07, 2021 at 04:15:02PM -0700, Sean Christopherson wrote:
> Check for a NULL page->mapping before dereferencing the mapping in
> page_is_secretmem(), as the page's mapping can be nullified while gup()
> is running, e.g. by reclaim or truncation.
>
> BUG: kernel NULL pointer dereference, address: 0000000000000068
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 0 P4D 0
> Oops: 0000 [#1] PREEMPT SMP NOPTI
> CPU: 6 PID: 4173897 Comm: CPU 3/KVM Tainted: G W
> RIP: 0010:internal_get_user_pages_fast+0x621/0x9d0
> Code: <48> 81 7a 68 80 08 04 bc 0f 85 21 ff ff 8 89 c7 be
> RSP: 0018:ffffaa90087679b0 EFLAGS: 00010046
> RAX: ffffe3f37905b900 RBX: 00007f2dd561e000 RCX: ffffe3f37905b934
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe3f37905b900
> ...
> CR2: 0000000000000068 CR3: 00000004c5898003 CR4: 00000000001726e0
> Call Trace:
> get_user_pages_fast_only+0x13/0x20
> hva_to_pfn+0xa9/0x3e0
> try_async_pf+0xa1/0x270
> direct_page_fault+0x113/0xad0
> kvm_mmu_page_fault+0x69/0x680
> vmx_handle_exit+0xe1/0x5d0
> kvm_arch_vcpu_ioctl_run+0xd81/0x1c70
> kvm_vcpu_ioctl+0x267/0x670
> __x64_sys_ioctl+0x83/0xa0
> do_syscall_64+0x56/0x80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: linux-mm@kvack.org
> Reported-by: Darrick J. Wong <djwong@kernel.org>
> Reported-by: Stephen <stephenackerman16@gmail.com>
> Tested-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
> include/linux/secretmem.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
> index 21c3771e6a56..988528b5da43 100644
> --- a/include/linux/secretmem.h
> +++ b/include/linux/secretmem.h
> @@ -23,7 +23,7 @@ static inline bool page_is_secretmem(struct page *page)
> mapping = (struct address_space *)
> ((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
>
> - if (mapping != page->mapping)
> + if (!mapping || mapping != page->mapping)
> return false;
>
> return mapping->a_ops == &secretmem_aops;
> --
> 2.33.0.882.g93a45727a2-goog
>
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-10-10 5:30 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-10-07 23:15 [PATCH] mm: Fix NULL page->mapping dereference in page_is_secretmem() Sean Christopherson
2021-10-08 10:46 ` David Hildenbrand
2021-10-08 14:17 ` Sean Christopherson
2021-10-10 5:29 ` Mike Rapoport
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