crypto: blkcipher: prefer strlcpy to strncpy
diff mbox

Message ID 1527572683-26098-1-git-send-email-nick.desaulniers@gmail.com
State Changes Requested
Delegated to: Herbert Xu
Headers show

Commit Message

Nick Desaulniers May 29, 2018, 5:44 a.m. UTC
Fixes stringop-truncation warnings from gcc-8.

Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
---
 crypto/ablkcipher.c | 8 ++++----
 crypto/blkcipher.c  | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

Comments

Eric Biggers May 29, 2018, 4:34 p.m. UTC | #1
On Mon, May 28, 2018 at 10:44:43PM -0700, Nick Desaulniers wrote:
> Fixes stringop-truncation warnings from gcc-8.
> 
> Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
> ---
>  crypto/ablkcipher.c | 8 ++++----
>  crypto/blkcipher.c  | 4 ++--
>  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
> index d880a48..e38867f 100644
> --- a/crypto/ablkcipher.c
> +++ b/crypto/ablkcipher.c
> @@ -370,8 +370,8 @@ static int crypto_ablkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
>  {
>  	struct crypto_report_blkcipher rblkcipher;
>  
> -	strncpy(rblkcipher.type, "ablkcipher", sizeof(rblkcipher.type));
> -	strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
> +	strlcpy(rblkcipher.type, "ablkcipher", sizeof(rblkcipher.type));
> +	strlcpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
>  		sizeof(rblkcipher.geniv));
>  
>  	rblkcipher.blocksize = alg->cra_blocksize;
> @@ -444,8 +444,8 @@ static int crypto_givcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
>  {
>  	struct crypto_report_blkcipher rblkcipher;
>  
> -	strncpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
> -	strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
> +	strlcpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
> +	strlcpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
>  		sizeof(rblkcipher.geniv));
>  
>  	rblkcipher.blocksize = alg->cra_blocksize;
> diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
> index 01c0d4a..ee88e48 100644
> --- a/crypto/blkcipher.c
> +++ b/crypto/blkcipher.c
> @@ -509,8 +509,8 @@ static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
>  {
>  	struct crypto_report_blkcipher rblkcipher;
>  
> -	strncpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
> -	strncpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
> +	strlcpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
> +	strlcpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
>  		sizeof(rblkcipher.geniv));
>  
>  	rblkcipher.blocksize = alg->cra_blocksize;
> -- 
> 2.7.4
> 

Hi Nick, this patch is wrong.  The 'struct crypto_report_blkcipher' is being
copied to userspace via netlink, so all bytes of it must be initialized.
strncpy() does this but strlcpy() does not.

I noticed that you're sending out some other patches replacing strncpy() with
strlcpy() too.  Can you please double check them for this same bug?

Thanks,

- Eric
Nick Desaulniers May 30, 2018, 2:03 a.m. UTC | #2
On Tue, May 29, 2018 at 9:34 AM, Eric Biggers <ebiggers3@gmail.com> wrote:
> On Mon, May 28, 2018 at 10:44:43PM -0700, Nick Desaulniers wrote:
>> Fixes stringop-truncation warnings from gcc-8.
>>
>> Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
>> ---
>>  crypto/ablkcipher.c | 8 ++++----
>>  crypto/blkcipher.c  | 4 ++--
>>  2 files changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
>> index d880a48..e38867f 100644
>> --- a/crypto/ablkcipher.c
>> +++ b/crypto/ablkcipher.c
>> @@ -370,8 +370,8 @@ static int crypto_ablkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
>>  {
>>       struct crypto_report_blkcipher rblkcipher;
>>
>> -     strncpy(rblkcipher.type, "ablkcipher", sizeof(rblkcipher.type));
>> -     strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
>> +     strlcpy(rblkcipher.type, "ablkcipher", sizeof(rblkcipher.type));
>> +     strlcpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
>>               sizeof(rblkcipher.geniv));
>>
>>       rblkcipher.blocksize = alg->cra_blocksize;
>> @@ -444,8 +444,8 @@ static int crypto_givcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
>>  {
>>       struct crypto_report_blkcipher rblkcipher;
>>
>> -     strncpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
>> -     strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
>> +     strlcpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
>> +     strlcpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
>>               sizeof(rblkcipher.geniv));
>>
>>       rblkcipher.blocksize = alg->cra_blocksize;
>> diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
>> index 01c0d4a..ee88e48 100644
>> --- a/crypto/blkcipher.c
>> +++ b/crypto/blkcipher.c
>> @@ -509,8 +509,8 @@ static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
>>  {
>>       struct crypto_report_blkcipher rblkcipher;
>>
>> -     strncpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
>> -     strncpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
>> +     strlcpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
>> +     strlcpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
>>               sizeof(rblkcipher.geniv));
>>
>>       rblkcipher.blocksize = alg->cra_blocksize;
>> --
>> 2.7.4
>>
>
> Hi Nick, this patch is wrong.  The 'struct crypto_report_blkcipher' is being
> copied to userspace via netlink, so all bytes of it must be initialized.
> strncpy() does this but strlcpy() does not.
>
> I noticed that you're sending out some other patches replacing strncpy() with
> strlcpy() too.  Can you please double check them for this same bug?
>
> Thanks,
>
> - Eric


Thanks for pointing out this subtlety, I've retracted the other patches.

Patch
diff mbox

diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index d880a48..e38867f 100644
--- a/crypto/ablkcipher.c
+++ b/crypto/ablkcipher.c
@@ -370,8 +370,8 @@  static int crypto_ablkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
 {
 	struct crypto_report_blkcipher rblkcipher;
 
-	strncpy(rblkcipher.type, "ablkcipher", sizeof(rblkcipher.type));
-	strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
+	strlcpy(rblkcipher.type, "ablkcipher", sizeof(rblkcipher.type));
+	strlcpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
 		sizeof(rblkcipher.geniv));
 
 	rblkcipher.blocksize = alg->cra_blocksize;
@@ -444,8 +444,8 @@  static int crypto_givcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
 {
 	struct crypto_report_blkcipher rblkcipher;
 
-	strncpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
-	strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
+	strlcpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
+	strlcpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
 		sizeof(rblkcipher.geniv));
 
 	rblkcipher.blocksize = alg->cra_blocksize;
diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
index 01c0d4a..ee88e48 100644
--- a/crypto/blkcipher.c
+++ b/crypto/blkcipher.c
@@ -509,8 +509,8 @@  static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
 {
 	struct crypto_report_blkcipher rblkcipher;
 
-	strncpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
-	strncpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
+	strlcpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
+	strlcpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
 		sizeof(rblkcipher.geniv));
 
 	rblkcipher.blocksize = alg->cra_blocksize;