LinuxLists.cc - [PATCH] crypto: qat - refactor deprecated strncpy

2023-09-13 09:07:07

Subject: [PATCH] crypto: qat - refactor deprecated strncpy

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

`buf` is expected to be NUL-terminated for its eventual use in
`kstrtoul()` and NUL-padding is not required.

Due to the above, a suitable replacement is `strscpy` [2] due to the
fact that it guarantees NUL-termination on the destination buffer.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested only.
---
drivers/crypto/intel/qat/qat_common/qat_uclo.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/intel/qat/qat_common/qat_uclo.c b/drivers/crypto/intel/qat/qat_common/qat_uclo.c
index ce837bcc1cab..e2f82128043e 100644
--- a/drivers/crypto/intel/qat/qat_common/qat_uclo.c
+++ b/drivers/crypto/intel/qat/qat_common/qat_uclo.c
@@ -200,7 +200,7 @@ static int qat_uclo_parse_num(char *str, unsigned int *num)
unsigned long ae = 0;
int i;

- strncpy(buf, str, 15);
+ strscpy(buf, str, sizeof(buf));
for (i = 0; i < 16; i++) {
if (!isdigit(buf[i])) {
buf[i] = '\0';

---
base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
change-id: 20230913-strncpy-drivers-crypto-intel-qat-qat_common-qat_uclo-c-0f4b16830f59

Best regards,
--
Justin Stitt <[email protected]>

2023-09-14 11:41:14

by Cabiddu, Giovanni

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Subject: Re: [PATCH] crypto: qat - refactor deprecated strncpy

2023-09-15 13:14:30

by Kees Cook

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Subject: Re: [PATCH] crypto: qat - refactor deprecated strncpy

On Wed, Sep 13, 2023 at 12:51:05AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> We should prefer more robust and less ambiguous string interfaces.
>
> `buf` is expected to be NUL-terminated for its eventual use in
> `kstrtoul()` and NUL-padding is not required.
>
> Due to the above, a suitable replacement is `strscpy` [2] due to the
> fact that it guarantees NUL-termination on the destination buffer.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested only.
> ---
> drivers/crypto/intel/qat/qat_common/qat_uclo.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/crypto/intel/qat/qat_common/qat_uclo.c b/drivers/crypto/intel/qat/qat_common/qat_uclo.c
> index ce837bcc1cab..e2f82128043e 100644
> --- a/drivers/crypto/intel/qat/qat_common/qat_uclo.c
> +++ b/drivers/crypto/intel/qat/qat_common/qat_uclo.c
> @@ -200,7 +200,7 @@ static int qat_uclo_parse_num(char *str, unsigned int *num)
> unsigned long ae = 0;
> int i;
>
> - strncpy(buf, str, 15);
> + strscpy(buf, str, sizeof(buf));
> for (i = 0; i < 16; i++) {
> if (!isdigit(buf[i])) {

I was initially worried when I saw this walking the entire contents, but
I see it is explicitly zeroed on the stack first, so this is fine:

char buf[16] = {0};

Reviewed-by: Kees Cook <[email protected]>

-Kees

> buf[i] = '\0';
>
> ---
> base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> change-id: 20230913-strncpy-drivers-crypto-intel-qat-qat_common-qat_uclo-c-0f4b16830f59
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>

--
Kees Cook

2023-09-20 05:21:42

by Herbert Xu

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