linux-kernel - Re: [PATCH] usb: typec: anx7411: Fix possible buffer overflow in anx7411_send

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Message-ID: <a1763e4f-cdf9-49d4-8421-f4cab902e277@wanadoo.fr>
Date: Sun, 17 Mar 2024 08:52:27 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: bazilevich@...amp.ru
Cc: gregkh@...uxfoundation.org, heikki.krogerus@...ux.intel.com,
 linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
 lvc-project@...uxtesting.org, xji@...logixsemi.com
Subject: Re: [PATCH] usb: typec: anx7411: Fix possible buffer overflow in
 anx7411_send_msg()

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@...lic.gmane.org>
> ---
>   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 */