linux-kernel - Re: [PATCH] greybus: firmware: use strscpy, fix tag size

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <2025061743-surging-legwarmer-b3a9@gregkh>
Date: Tue, 17 Jun 2025 15:16:06 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Pranav Tyagi <pranav.tyagi03@...il.com>
Cc: johan@...nel.org, elder@...nel.org, vireshk@...nel.org,
	greybus-dev@...ts.linaro.org, linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org, skhan@...uxfoundation.org,
	linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH] greybus: firmware: use strscpy, fix tag size

On Tue, Jun 17, 2025 at 06:21:37PM +0530, Pranav Tyagi wrote:
> Increase the size of firmware_tag arrays in the following structs from
> GB_FIRMWARE_U_TAG_MAX_SIZE to GB_FIRMWARE_U_TAG_MAX_SIZE + 1 to
> accommodate null termination:
> 	- fw_mgmt_ioc_intf_load_and_validate
> 	- fw_mgmt_ioc_get_backend_version
> 	- fw_mgmt_ioc_backend_fw_update
> 	- fw_mgmt_ioc_get_intf_version
> 
> Replace strncpy() with strscpy() to ensure proper null termination as
> firmware_tag is interpreted as a null-terminated string
> and printed with %s.
> 
> Signed-off-by: Pranav Tyagi <pranav.tyagi03@...il.com>
> ---
>  .../greybus/Documentation/firmware/firmware.c        | 12 ++++++------
>  drivers/staging/greybus/greybus_firmware.h           |  8 ++++----
>  2 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/staging/greybus/Documentation/firmware/firmware.c b/drivers/staging/greybus/Documentation/firmware/firmware.c
> index 765d69faa9cc..3b4061f4b34a 100644
> --- a/drivers/staging/greybus/Documentation/firmware/firmware.c
> +++ b/drivers/staging/greybus/Documentation/firmware/firmware.c
> @@ -63,8 +63,8 @@ static int update_intf_firmware(int fd)
>  	intf_load.major = 0;
>  	intf_load.minor = 0;
>  
> -	strncpy((char *)&intf_load.firmware_tag, firmware_tag,
> -		GB_FIRMWARE_U_TAG_MAX_SIZE);
> +	strscpy((char *)&intf_load.firmware_tag, firmware_tag,
> +		GB_FIRMWARE_U_TAG_MAX_SIZE + 1);
>  
>  	ret = ioctl(fd, FW_MGMT_IOC_INTF_LOAD_AND_VALIDATE, &intf_load);
>  	if (ret < 0) {
> @@ -101,8 +101,8 @@ static int update_backend_firmware(int fd)
>  	/* Get Backend Firmware Version */
>  	printf("Getting Backend Firmware Version\n");
>  
> -	strncpy((char *)&backend_fw_info.firmware_tag, firmware_tag,
> -		GB_FIRMWARE_U_TAG_MAX_SIZE);
> +	strscpy((char *)&backend_fw_info.firmware_tag, firmware_tag,
> +		GB_FIRMWARE_U_TAG_MAX_SIZE + 1);
>  
>  retry_fw_version:
>  	ret = ioctl(fd, FW_MGMT_IOC_GET_BACKEND_FW, &backend_fw_info);
> @@ -129,8 +129,8 @@ static int update_backend_firmware(int fd)
>  	/* Try Backend Firmware Update over Unipro */
>  	printf("Updating Backend Firmware\n");
>  
> -	strncpy((char *)&backend_update.firmware_tag, firmware_tag,
> -		GB_FIRMWARE_U_TAG_MAX_SIZE);
> +	strscpy((char *)&backend_update.firmware_tag, firmware_tag,
> +		GB_FIRMWARE_U_TAG_MAX_SIZE + 1);
>  
>  retry_fw_update:
>  	backend_update.status = 0;
> diff --git a/drivers/staging/greybus/greybus_firmware.h b/drivers/staging/greybus/greybus_firmware.h
> index b6042a82ada4..ad5b2c8a6461 100644
> --- a/drivers/staging/greybus/greybus_firmware.h
> +++ b/drivers/staging/greybus/greybus_firmware.h
> @@ -38,20 +38,20 @@
>  
>  /* IOCTL support */
>  struct fw_mgmt_ioc_get_intf_version {
> -	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE];
> +	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE + 1];
>  	__u16 major;
>  	__u16 minor;
>  } __packed;
>  
>  struct fw_mgmt_ioc_get_backend_version {
> -	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE];
> +	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE + 1];
>  	__u16 major;
>  	__u16 minor;
>  	__u8 status;
>  } __packed;
>  
>  struct fw_mgmt_ioc_intf_load_and_validate {
> -	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE];
> +	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE + 1];
>  	__u8 load_method;
>  	__u8 status;
>  	__u16 major;
> @@ -59,7 +59,7 @@ struct fw_mgmt_ioc_intf_load_and_validate {
>  } __packed;
>  
>  struct fw_mgmt_ioc_backend_fw_update {
> -	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE];
> +	__u8 firmware_tag[GB_FIRMWARE_U_TAG_MAX_SIZE + 1];
>  	__u8 status;
>  } __packed;
>  

You are changing the size of a userspace structure here, are you SURE
this is allowed?

How was this tested?

thanks,

greg k-h