2018-05-29 05:47:01

by Nick Desaulniers

Subject: [PATCH] crypto: blkcipher: prefer strlcpy to strncpy

Fixes stringop-truncation warnings from gcc-8.

Signed-off-by: Nick Desaulniers <[email protected]>
---
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

2018-05-29 16:35:17

by Eric Biggers

Subject: Re: [PATCH] crypto: blkcipher: prefer strlcpy to strncpy

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 <[email protected]>
> ---
> 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

2018-05-30 02:04:57

by Nick Desaulniers

Subject: Re: [PATCH] crypto: blkcipher: prefer strlcpy to strncpy

On Tue, May 29, 2018 at 9:34 AM, Eric Biggers <[email protected]> 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 <[email protected]>
>> ---
>> 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.