diff mbox series

[v2] crypto: Use struct_size() helper in kmalloc()

Message ID 20220518005639.181640-1-guozihua@huawei.com (mailing list archive)
State New
Headers show
Series [v2] crypto: Use struct_size() helper in kmalloc() | expand

Commit Message

GUO Zihua May 18, 2022, 12:56 a.m. UTC
Make use of struct_size() heler for structures containing flexible array
member instead of sizeof() which prevents potential issues as well as
addressing the following sparse warning:

crypto/asymmetric_keys/asymmetric_type.c:155:23: warning: using sizeof
on a flexible structure
crypto/asymmetric_keys/asymmetric_type.c:247:28: warning: using sizeof
on a flexible structure

Reference: https://github.com/KSPP/linux/issues/174

Signed-off-by: GUO Zihua <guozihua@huawei.com>

---

v2:
    Use size_add() helper following Kees Cook's suggestion.
---
 crypto/asymmetric_keys/asymmetric_type.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Gustavo A. R. Silva May 18, 2022, 4:55 a.m. UTC | #1
On Wed, May 18, 2022 at 08:56:39AM +0800, GUO Zihua wrote:
> Make use of struct_size() heler for structures containing flexible array
> member instead of sizeof() which prevents potential issues as well as
> addressing the following sparse warning:
> 
> crypto/asymmetric_keys/asymmetric_type.c:155:23: warning: using sizeof
> on a flexible structure
> crypto/asymmetric_keys/asymmetric_type.c:247:28: warning: using sizeof
> on a flexible structure

The warnings above are not silenced with this patch as struct_size()
internally use sizeof on the struct-with-flex-array.

However, the use of struct_size() instead of the open-coded expressions
in the calls to kmalloc() is correct.

> 
> Reference: https://github.com/KSPP/linux/issues/174

I updated this issue on the issue tracker. Please, from now on, just
use that issue as a list of potential open-coded instances to be
audited. :)

> 
> Signed-off-by: GUO Zihua <guozihua@huawei.com>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> 
> ---
> 
> v2:
>     Use size_add() helper following Kees Cook's suggestion.
> ---
>  crypto/asymmetric_keys/asymmetric_type.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
> index 41a2f0eb4ce4..e020222b1fe5 100644
> --- a/crypto/asymmetric_keys/asymmetric_type.c
> +++ b/crypto/asymmetric_keys/asymmetric_type.c
> @@ -152,7 +152,7 @@ struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
>  {
>  	struct asymmetric_key_id *kid;
>  
> -	kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
> +	kid = kmalloc(struct_size(kid, data, size_add(len_1, len_2)),
>  		      GFP_KERNEL);
>  	if (!kid)
>  		return ERR_PTR(-ENOMEM);
> @@ -244,7 +244,7 @@ struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
>  	if (asciihexlen & 1)
>  		return ERR_PTR(-EINVAL);
>  
> -	match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
> +	match_id = kmalloc(struct_size(match_id, data, asciihexlen / 2),
>  			   GFP_KERNEL);
>  	if (!match_id)
>  		return ERR_PTR(-ENOMEM);
> -- 
> 2.36.0
>
GUO Zihua May 18, 2022, 6:21 a.m. UTC | #2
On 2022/5/18 12:55, Gustavo A. R. Silva wrote:
> On Wed, May 18, 2022 at 08:56:39AM +0800, GUO Zihua wrote:
>> Make use of struct_size() heler for structures containing flexible array
>> member instead of sizeof() which prevents potential issues as well as
>> addressing the following sparse warning:
>>
>> crypto/asymmetric_keys/asymmetric_type.c:155:23: warning: using sizeof
>> on a flexible structure
>> crypto/asymmetric_keys/asymmetric_type.c:247:28: warning: using sizeof
>> on a flexible structure
> 
> The warnings above are not silenced with this patch as struct_size()
> internally use sizeof on the struct-with-flex-array.
> 
> However, the use of struct_size() instead of the open-coded expressions
> in the calls to kmalloc() is correct.
> 
>>
>> Reference: https://github.com/KSPP/linux/issues/174
> 
> I updated this issue on the issue tracker. Please, from now on, just
> use that issue as a list of potential open-coded instances to be
> audited. :)
> 
>>
>> Signed-off-by: GUO Zihua <guozihua@huawei.com>
> 
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> 
> Thanks
> --
> Gustavo
> 
>>
>> ---
>>
>> v2:
>>      Use size_add() helper following Kees Cook's suggestion.
>> ---
>>   crypto/asymmetric_keys/asymmetric_type.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
>> index 41a2f0eb4ce4..e020222b1fe5 100644
>> --- a/crypto/asymmetric_keys/asymmetric_type.c
>> +++ b/crypto/asymmetric_keys/asymmetric_type.c
>> @@ -152,7 +152,7 @@ struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
>>   {
>>   	struct asymmetric_key_id *kid;
>>   
>> -	kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
>> +	kid = kmalloc(struct_size(kid, data, size_add(len_1, len_2)),
>>   		      GFP_KERNEL);
>>   	if (!kid)
>>   		return ERR_PTR(-ENOMEM);
>> @@ -244,7 +244,7 @@ struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
>>   	if (asciihexlen & 1)
>>   		return ERR_PTR(-EINVAL);
>>   
>> -	match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
>> +	match_id = kmalloc(struct_size(match_id, data, asciihexlen / 2),
>>   			   GFP_KERNEL);
>>   	if (!match_id)
>>   		return ERR_PTR(-ENOMEM);
>> -- 
>> 2.36.0
>>
> .

Thanks for the review Gustavo.

I'll send a v3 patch and update the commit message. Maybe refer to the 
mail from Linus instead.
diff mbox series

Patch

diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index 41a2f0eb4ce4..e020222b1fe5 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -152,7 +152,7 @@  struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
 {
 	struct asymmetric_key_id *kid;
 
-	kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
+	kid = kmalloc(struct_size(kid, data, size_add(len_1, len_2)),
 		      GFP_KERNEL);
 	if (!kid)
 		return ERR_PTR(-ENOMEM);
@@ -244,7 +244,7 @@  struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
 	if (asciihexlen & 1)
 		return ERR_PTR(-EINVAL);
 
-	match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
+	match_id = kmalloc(struct_size(match_id, data, asciihexlen / 2),
 			   GFP_KERNEL);
 	if (!match_id)
 		return ERR_PTR(-ENOMEM);