Re: [PATCH] usb: typec: anx7411: Fix possible buffer overflow in anx7411_send_msg()

[Christophe JAILLET]

Le 16/03/2024 à 21:33, Grigory Bazilevich a écrit :
> Passing a size argument greater than or equal to MAX_BUF_LEN causes
> a buffer overflow when the checksum is written.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: fe6d8a9c8e64 ("usb: typec: anx7411: Add Analogix PD ANX7411 support")
> Signed-off-by: Grigory Bazilevich <bazilevich-vHv2KSI2GGSHXe+LvDLADg@xxxxxxxxxxxxxxxx>
> ---
>   drivers/usb/typec/anx7411.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/typec/anx7411.c b/drivers/usb/typec/anx7411.c
> index b12a07edc71b..70ba56dfb22b 100644
> --- a/drivers/usb/typec/anx7411.c
> +++ b/drivers/usb/typec/anx7411.c
> @@ -733,7 +733,7 @@ static int anx7411_send_msg(struct anx7411_data *ctx, u8 type, u8 *buf, u8 size)
>   	u8 crc;
>   	int ret;
>   
> -	size = min_t(u8, size, (u8)MAX_BUF_LEN);
> +	size = min_t(u8, size, (u8)(MAX_BUF_LEN - 1));

Hi,

with "min_t(u8, ...", is the casting needed?

CJ

>   	memcpy(msg->buf, buf, size);
>   	msg->msg_type = type;
>   	/* msg len equals buffer length + msg_type */