Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[Michael Holzheu]

Am Thu, 1 Sep 2016 17:39:02 +0200
schrieb Paolo Bonzini :

> 
> 
> On 01/09/2016 12:32, Heiko Carstens wrote:
> > On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
> >> From: Markus Elfring 
> >> Date: Thu, 1 Sep 2016 11:30:58 +0200
> >>
> >> A multiplication for the size determination of a memory allocation
> >> indicated that an array data structure should be processed.
> >> Thus use the corresponding function "kmalloc_array".
> >>
> >> This issue was detected by using the Coccinelle software.
> >>
> >> Signed-off-by: Markus Elfring 
> >> ---
> >>  arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
> >>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/s390/hypfs/hypfs_diag0c.c
> >> b/arch/s390/hypfs/hypfs_diag0c.c index 0f1927c..61418a8 100644
> >> --- a/arch/s390/hypfs/hypfs_diag0c.c
> >> +++ b/arch/s390/hypfs/hypfs_diag0c.c
> >> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
> >>  
> >>get_online_cpus();
> >>cpu_count = num_online_cpus();
> >> -  cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(),
> >> GFP_KERNEL);
> >> +  cpu_vec = kmalloc_array(num_possible_cpus(),
> >> +  sizeof(*cpu_vec),
> >> +  GFP_KERNEL);
> > 
> > How does this improve the situation? For any real life scenario
> > this can't overflow, but it does add an extra (pointless) runtime
> > check, since num_possible_cpus() is not a compile time constant.
> > 
> > So, why is this an "issue"?
> 
> It's not an issue but I for one still prefer consistent use of
> kmalloc_array and kcalloc.

Hello Paolo,

I will keep this in mind for future code, but would prefer not changing
this now.

Michael

Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[Michael Holzheu]

Am Thu, 1 Sep 2016 17:39:02 +0200
schrieb Paolo Bonzini :

> 
> 
> On 01/09/2016 12:32, Heiko Carstens wrote:
> > On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
> >> From: Markus Elfring 
> >> Date: Thu, 1 Sep 2016 11:30:58 +0200
> >>
> >> A multiplication for the size determination of a memory allocation
> >> indicated that an array data structure should be processed.
> >> Thus use the corresponding function "kmalloc_array".
> >>
> >> This issue was detected by using the Coccinelle software.
> >>
> >> Signed-off-by: Markus Elfring 
> >> ---
> >>  arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
> >>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/s390/hypfs/hypfs_diag0c.c
> >> b/arch/s390/hypfs/hypfs_diag0c.c index 0f1927c..61418a8 100644
> >> --- a/arch/s390/hypfs/hypfs_diag0c.c
> >> +++ b/arch/s390/hypfs/hypfs_diag0c.c
> >> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
> >>  
> >>get_online_cpus();
> >>cpu_count = num_online_cpus();
> >> -  cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(),
> >> GFP_KERNEL);
> >> +  cpu_vec = kmalloc_array(num_possible_cpus(),
> >> +  sizeof(*cpu_vec),
> >> +  GFP_KERNEL);
> > 
> > How does this improve the situation? For any real life scenario
> > this can't overflow, but it does add an extra (pointless) runtime
> > check, since num_possible_cpus() is not a compile time constant.
> > 
> > So, why is this an "issue"?
> 
> It's not an issue but I for one still prefer consistent use of
> kmalloc_array and kcalloc.

Hello Paolo,

I will keep this in mind for future code, but would prefer not changing
this now.

Michael

Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[Paolo Bonzini]

On 01/09/2016 12:32, Heiko Carstens wrote:
> On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
>> From: Markus Elfring 
>> Date: Thu, 1 Sep 2016 11:30:58 +0200
>>
>> A multiplication for the size determination of a memory allocation
>> indicated that an array data structure should be processed.
>> Thus use the corresponding function "kmalloc_array".
>>
>> This issue was detected by using the Coccinelle software.
>>
>> Signed-off-by: Markus Elfring 
>> ---
>>  arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
>> index 0f1927c..61418a8 100644
>> --- a/arch/s390/hypfs/hypfs_diag0c.c
>> +++ b/arch/s390/hypfs/hypfs_diag0c.c
>> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
>>  
>>  get_online_cpus();
>>  cpu_count = num_online_cpus();
>> -cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
>> +cpu_vec = kmalloc_array(num_possible_cpus(),
>> +sizeof(*cpu_vec),
>> +GFP_KERNEL);
> 
> How does this improve the situation? For any real life scenario this can't
> overflow, but it does add an extra (pointless) runtime check, since
> num_possible_cpus() is not a compile time constant.
> 
> So, why is this an "issue"?

It's not an issue but I for one still prefer consistent use of
kmalloc_array and kcalloc.

Paolo

Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[Paolo Bonzini]

On 01/09/2016 12:32, Heiko Carstens wrote:
> On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
>> From: Markus Elfring 
>> Date: Thu, 1 Sep 2016 11:30:58 +0200
>>
>> A multiplication for the size determination of a memory allocation
>> indicated that an array data structure should be processed.
>> Thus use the corresponding function "kmalloc_array".
>>
>> This issue was detected by using the Coccinelle software.
>>
>> Signed-off-by: Markus Elfring 
>> ---
>>  arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
>> index 0f1927c..61418a8 100644
>> --- a/arch/s390/hypfs/hypfs_diag0c.c
>> +++ b/arch/s390/hypfs/hypfs_diag0c.c
>> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
>>  
>>  get_online_cpus();
>>  cpu_count = num_online_cpus();
>> -cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
>> +cpu_vec = kmalloc_array(num_possible_cpus(),
>> +sizeof(*cpu_vec),
>> +GFP_KERNEL);
> 
> How does this improve the situation? For any real life scenario this can't
> overflow, but it does add an extra (pointless) runtime check, since
> num_possible_cpus() is not a compile time constant.
> 
> So, why is this an "issue"?

It's not an issue but I for one still prefer consistent use of
kmalloc_array and kcalloc.

Paolo

Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[Heiko Carstens]

On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
> From: Markus Elfring 
> Date: Thu, 1 Sep 2016 11:30:58 +0200
> 
> A multiplication for the size determination of a memory allocation
> indicated that an array data structure should be processed.
> Thus use the corresponding function "kmalloc_array".
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring 
> ---
>  arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
> index 0f1927c..61418a8 100644
> --- a/arch/s390/hypfs/hypfs_diag0c.c
> +++ b/arch/s390/hypfs/hypfs_diag0c.c
> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
>  
>   get_online_cpus();
>   cpu_count = num_online_cpus();
> - cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
> + cpu_vec = kmalloc_array(num_possible_cpus(),
> + sizeof(*cpu_vec),
> + GFP_KERNEL);

How does this improve the situation? For any real life scenario this can't
overflow, but it does add an extra (pointless) runtime check, since
num_possible_cpus() is not a compile time constant.

So, why is this an "issue"?

Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[Heiko Carstens]

On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
> From: Markus Elfring 
> Date: Thu, 1 Sep 2016 11:30:58 +0200
> 
> A multiplication for the size determination of a memory allocation
> indicated that an array data structure should be processed.
> Thus use the corresponding function "kmalloc_array".
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring 
> ---
>  arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
> index 0f1927c..61418a8 100644
> --- a/arch/s390/hypfs/hypfs_diag0c.c
> +++ b/arch/s390/hypfs/hypfs_diag0c.c
> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
>  
>   get_online_cpus();
>   cpu_count = num_online_cpus();
> - cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
> + cpu_vec = kmalloc_array(num_possible_cpus(),
> + sizeof(*cpu_vec),
> + GFP_KERNEL);

How does this improve the situation? For any real life scenario this can't
overflow, but it does add an extra (pointless) runtime check, since
num_possible_cpus() is not a compile time constant.

So, why is this an "issue"?

[PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[SF Markus Elfring]

From: Markus Elfring 
Date: Thu, 1 Sep 2016 11:30:58 +0200

A multiplication for the size determination of a memory allocation
indicated that an array data structure should be processed.
Thus use the corresponding function "kmalloc_array".

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring 
---
 arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
index 0f1927c..61418a8 100644
--- a/arch/s390/hypfs/hypfs_diag0c.c
+++ b/arch/s390/hypfs/hypfs_diag0c.c
@@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
 
get_online_cpus();
cpu_count = num_online_cpus();
-   cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
+   cpu_vec = kmalloc_array(num_possible_cpus(),
+   sizeof(*cpu_vec),
+   GFP_KERNEL);
if (!cpu_vec)
goto fail_put_online_cpus;
/* Note: Diag 0c needs 8 byte alignment and real storage */
-- 
2.9.3

[PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()

[SF Markus Elfring]

From: Markus Elfring 
Date: Thu, 1 Sep 2016 11:30:58 +0200

A multiplication for the size determination of a memory allocation
indicated that an array data structure should be processed.
Thus use the corresponding function "kmalloc_array".

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring 
---
 arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
index 0f1927c..61418a8 100644
--- a/arch/s390/hypfs/hypfs_diag0c.c
+++ b/arch/s390/hypfs/hypfs_diag0c.c
@@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
 
get_online_cpus();
cpu_count = num_online_cpus();
-   cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
+   cpu_vec = kmalloc_array(num_possible_cpus(),
+   sizeof(*cpu_vec),
+   GFP_KERNEL);
if (!cpu_vec)
goto fail_put_online_cpus;
/* Note: Diag 0c needs 8 byte alignment and real storage */
-- 
2.9.3