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Groups > linux.kernel > #1621249 > unrolled thread

[PATCH] mm/migrate: check for null vma before dereferencing it

Started byColin King <colin.king@canonical.com>
First post2017-04-11 15:00 +0200
Last post2017-04-11 23:50 +0200
Articles 4 — 3 participants

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  [PATCH] mm/migrate: check for null vma before dereferencing it Colin King <colin.king@canonical.com> - 2017-04-11 15:00 +0200
    Re: [PATCH] mm/migrate: check for null vma before dereferencing it Andrew Morton <akpm@linux-foundation.org> - 2017-04-11 23:30 +0200
      Re: [PATCH] mm/migrate: check for null vma before dereferencing it Colin Ian King <colin.king@canonical.com> - 2017-04-11 23:40 +0200
        Re: [PATCH] mm/migrate: check for null vma before dereferencing it Andrew Morton <akpm@linux-foundation.org> - 2017-04-11 23:50 +0200

#1621249 — [PATCH] mm/migrate: check for null vma before dereferencing it

FromColin King <colin.king@canonical.com>
Date2017-04-11 15:00 +0200
Subject[PATCH] mm/migrate: check for null vma before dereferencing it
Message-ID<tv3yN-77s-3@gated-at.bofh.it>
From: Colin Ian King <colin.king@canonical.com>

check if vma is null before dereferencing it, this avoiding any
potential null pointer dereferences on vma via the is_vm_hugetlb_page
call or the direct vma->vm_flags reference.

Detected with CoverityScan, CID#1427995 ("Dereference before null check")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 mm/migrate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 7958dfa01b16..039f7bc3b9ee 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2757,10 +2757,10 @@ int migrate_vma(const struct migrate_vma_ops *ops,
 	/* Sanity check the arguments */
 	start &= PAGE_MASK;
 	end &= PAGE_MASK;
-	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
-		return -EINVAL;
 	if (!vma || !ops || !src || !dst || start >= end)
 		return -EINVAL;
+	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
+		return -EINVAL;
 	if (start < vma->vm_start || start >= vma->vm_end)
 		return -EINVAL;
 	if (end <= vma->vm_start || end > vma->vm_end)
-- 
2.11.0

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#1621636

FromAndrew Morton <akpm@linux-foundation.org>
Date2017-04-11 23:30 +0200
Message-ID<tvbwm-3ZY-17@gated-at.bofh.it>
In reply to#1621249
On Tue, 11 Apr 2017 13:51:02 +0100 Colin King <colin.king@canonical.com> wrote:

> From: Colin Ian King <colin.king@canonical.com>
> 
> check if vma is null before dereferencing it, this avoiding any
> potential null pointer dereferences on vma via the is_vm_hugetlb_page
> call or the direct vma->vm_flags reference.
> 
> Detected with CoverityScan, CID#1427995 ("Dereference before null check")
> 
> ...
>
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2757,10 +2757,10 @@ int migrate_vma(const struct migrate_vma_ops *ops,
>  	/* Sanity check the arguments */
>  	start &= PAGE_MASK;
>  	end &= PAGE_MASK;
> -	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
> -		return -EINVAL;
>  	if (!vma || !ops || !src || !dst || start >= end)
>  		return -EINVAL;
> +	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
> +		return -EINVAL;
>  	if (start < vma->vm_start || start >= vma->vm_end)
>  		return -EINVAL;
>  	if (end <= vma->vm_start || end > vma->vm_end)

I don't know what kernel version this is against but I don't think it's
anything recent?

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#1621640

FromColin Ian King <colin.king@canonical.com>
Date2017-04-11 23:40 +0200
Message-ID<tvbG1-43u-11@gated-at.bofh.it>
In reply to#1621636
On 11/04/17 22:26, Andrew Morton wrote:
> On Tue, 11 Apr 2017 13:51:02 +0100 Colin King <colin.king@canonical.com> wrote:
> 
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> check if vma is null before dereferencing it, this avoiding any
>> potential null pointer dereferences on vma via the is_vm_hugetlb_page
>> call or the direct vma->vm_flags reference.
>>
>> Detected with CoverityScan, CID#1427995 ("Dereference before null check")
>>
>> ...
>>
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -2757,10 +2757,10 @@ int migrate_vma(const struct migrate_vma_ops *ops,
>>  	/* Sanity check the arguments */
>>  	start &= PAGE_MASK;
>>  	end &= PAGE_MASK;
>> -	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
>> -		return -EINVAL;
>>  	if (!vma || !ops || !src || !dst || start >= end)
>>  		return -EINVAL;
>> +	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
>> +		return -EINVAL;
>>  	if (start < vma->vm_start || start >= vma->vm_end)
>>  		return -EINVAL;
>>  	if (end <= vma->vm_start || end > vma->vm_end)
> 
> I don't know what kernel version this is against but I don't think it's
> anything recent?

I should have said it was against linux-next
> 
> --
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#1621645

FromAndrew Morton <akpm@linux-foundation.org>
Date2017-04-11 23:50 +0200
Message-ID<tvbPH-471-1@gated-at.bofh.it>
In reply to#1621640
On Tue, 11 Apr 2017 22:31:12 +0100 Colin Ian King <colin.king@canonical.com> wrote:

> On 11/04/17 22:26, Andrew Morton wrote:
> > On Tue, 11 Apr 2017 13:51:02 +0100 Colin King <colin.king@canonical.com> wrote:
> > 
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> check if vma is null before dereferencing it, this avoiding any
> >> potential null pointer dereferences on vma via the is_vm_hugetlb_page
> >> call or the direct vma->vm_flags reference.
> >>
> >> Detected with CoverityScan, CID#1427995 ("Dereference before null check")
> >>
> >> ...
> >>
> >> --- a/mm/migrate.c
> >> +++ b/mm/migrate.c
> >> @@ -2757,10 +2757,10 @@ int migrate_vma(const struct migrate_vma_ops *ops,
> >>  	/* Sanity check the arguments */
> >>  	start &= PAGE_MASK;
> >>  	end &= PAGE_MASK;
> >> -	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
> >> -		return -EINVAL;
> >>  	if (!vma || !ops || !src || !dst || start >= end)
> >>  		return -EINVAL;
> >> +	if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
> >> +		return -EINVAL;
> >>  	if (start < vma->vm_start || start >= vma->vm_end)
> >>  		return -EINVAL;
> >>  	if (end <= vma->vm_start || end > vma->vm_end)
> > 
> > I don't know what kernel version this is against but I don't think it's
> > anything recent?
> 
> I should have said it was against linux-next

ah, it modifies an HMM patch which I dropped a couple of hours ago.  One
for Jerome, please.

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