linux-kernel - Re: [PATCH] usb: fix slab-out-of-bounds Read in cougar_report

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Message-ID: <ZqqUnrJkvfsSS9Ag@homearch.localdomain>
Date: Wed, 31 Jul 2024 21:46:38 +0200
From: Silvan Jegen <s.jegen@...il.com>
To: Camila Alvarez <cam.alvarez.i@...il.com>
Cc: Jiri Kosina <jikos@...nel.org>, Benjamin Tissoires <bentiss@...nel.org>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	syzbot+24c0361074799d02c452@...kaller.appspotmail.com
Subject: Re: [PATCH] usb: fix slab-out-of-bounds Read in cougar_report_fixup

On Tue, Jul 30, 2024 at 07:42:43PM -0400, Camila Alvarez wrote:
> report_fixup for the Cougar 500k Gaming Keyboard was not verifying
> that the report descriptor size was correct before accessing it
> 
> Reported-by: syzbot+24c0361074799d02c452@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=24c0361074799d02c452
> Signed-off-by: Camila Alvarez <cam.alvarez.i@...il.com>
> ---
>  drivers/hid/hid-cougar.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

This LGTM!

Reviewed-by: Silvan Jegen <s.jegen@...il.com>

> 
> diff --git a/drivers/hid/hid-cougar.c b/drivers/hid/hid-cougar.c
> index cb8bd8aae15b..0fa785f52707 100644
> --- a/drivers/hid/hid-cougar.c
> +++ b/drivers/hid/hid-cougar.c
> @@ -106,7 +106,7 @@ static void cougar_fix_g6_mapping(void)
>  static __u8 *cougar_report_fixup(struct hid_device *hdev, __u8 *rdesc,
>  				 unsigned int *rsize)
>  {
> -	if (rdesc[2] == 0x09 && rdesc[3] == 0x02 &&
> +	if (*rsize >= 117 && rdesc[2] == 0x09 && rdesc[3] == 0x02 &&
>  	    (rdesc[115] | rdesc[116] << 8) >= HID_MAX_USAGES) {
>  		hid_info(hdev,
>  			"usage count exceeds max: fixing up report descriptor\n");
> -- 
> 2.34.1
> 
>