linux-hardening - Re: [PATCH] staging: rtl8723bs: Allocate full pwep structure

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Message-ID: <38d31460-f3e0-1260-05c5-406a05d9fb37@wanadoo.fr>
Date:   Sat, 18 Jun 2022 09:51:36 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Kees Cook <keescook@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Fabio Aiuto <fabioaiuto83@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        linux-staging@...ts.linux.dev,
        Michael Straube <straube.linux@...il.com>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH] staging: rtl8723bs: Allocate full pwep structure

Le 08/06/2022 à 23:55, Kees Cook a écrit :
> The pwep allocation was always being allocated smaller than the true
> structure size. Avoid this by always allocating the full structure.
> Found with GCC 12 and -Warray-bounds:
> 
> ../drivers/staging/rtl8723bs/os_dep/ioctl_linux.c: In function 'rtw_set_encryption':
> ../drivers/staging/rtl8723bs/os_dep/ioctl_linux.c:591:29: warning: array subscript 'struct ndis_802_11_wep[0]' is partly outside array bounds of 'void[25]' [-Warray-bounds]
>    591 |                         pwep->length = wep_total_len;
>        |                             ^~
> 
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Fabio Aiuto <fabioaiuto83@...il.com>
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: linux-staging@...ts.linux.dev
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>   drivers/staging/rtl8723bs/os_dep/ioctl_linux.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
> index ece97e37ac91..30374a820496 100644
> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
> @@ -90,7 +90,8 @@ static int wpa_set_encryption(struct net_device *dev, struct ieee_param *param,
>   		if (wep_key_len > 0) {
>   			wep_key_len = wep_key_len <= 5 ? 5 : 13;
>   			wep_total_len = wep_key_len + FIELD_OFFSET(struct ndis_802_11_wep, key_material);
> -			pwep = kzalloc(wep_total_len, GFP_KERNEL);
> +			/* Allocate a full structure to avoid potentially running off the end. */
> +			pwep = kzalloc(sizeof(*pwep), GFP_KERNEL);
>   			if (!pwep) {
>   				ret = -ENOMEM;
>   				goto exit;
> @@ -582,7 +583,8 @@ static int rtw_set_encryption(struct net_device *dev, struct ieee_param *param,
>   		if (wep_key_len > 0) {
>   			wep_key_len = wep_key_len <= 5 ? 5 : 13;
>   			wep_total_len = wep_key_len + FIELD_OFFSET(struct ndis_802_11_wep, key_material);
> -			pwep = kzalloc(wep_total_len, GFP_KERNEL);
> +			/* Allocate a full structure to avoid potentially running off the end. */
> +			pwep = kzalloc(sizeof(*pwep), GFP_KERNEL);
>   			if (!pwep)

Hi,

while at it (and un-related tyo your patch), I think that 'ret' should 
also be updated here, otherwise we return 0.

CJ

>   				goto exit;
>