Re: [PATCH 03/64] rpmsg: glink: Replace strncpy() with strscpy_pad()

Gustavo A. R. Silva
2021-07-28T02:05:20Z

On Tue, Jul 27, 2021 at 01:57:54PM -0700, Kees Cook wrote:
> The use of strncpy() is considered deprecated for NUL-terminated
> strings[1]. Replace strncpy() with strscpy_pad() (as it seems this case
> expects the NUL padding to fill the allocation following the flexible
> array). This additionally silences a warning seen when building under
> -Warray-bounds:
>
> ./include/linux/fortify-string.h:38:30: warning: '__builtin_strncpy' offset 24 from the object at '__mptr' is out of the bounds of referenced subobject 'data' with type 'u8[]' {aka 'unsigned char[]'} at offset 24 [-Warray-bounds]
> 38 | #define __underlying_strncpy __builtin_strncpy
> | ^
> ./include/linux/fortify-string.h:50:9: note: in expansion of macro '__underlying_strncpy'
> 50 | return __underlying_strncpy(p, q, size);
> | ^~~~~~~~~~~~~~~~~~~~
> drivers/rpmsg/qcom_glink_native.c: In function 'qcom_glink_work':
> drivers/rpmsg/qcom_glink_native.c:36:5: note: subobject 'data' declared here
> 36 | u8 data[];
> | ^~~~
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
>
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
--
Gustavo

> ---
> drivers/rpmsg/qcom_glink_native.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 05533c71b10e..c7b9de655080 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -1440,7 +1440,7 @@ static int qcom_glink_rx_open(struct qcom_glink *glink, unsigned int rcid,
> }
>
> rpdev->ept = &channel->ept;
> - strncpy(rpdev->id.name, name, RPMSG_NAME_SIZE);
> + strscpy_pad(rpdev->id.name, name, RPMSG_NAME_SIZE);
> rpdev->src = RPMSG_ADDR_ANY;
> rpdev->dst = RPMSG_ADDR_ANY;
> rpdev->ops = &glink_device_ops;
> --
> 2.30.2
>