linux-kernel - Re: [PATCH] watchdog: aspeed: fix integer overflow in set

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

Message-ID: <469ac948-d65b-471f-102f-726466c19c5c@roeck-us.net>
Date:   Thu, 15 Apr 2021 17:50:32 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     rentao.bupt@...il.com, Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        openbmc@...ts.ozlabs.org, Tao Ren <taoren@...com>,
        Amithash Prasad <amithash@...com>
Subject: Re: [PATCH] watchdog: aspeed: fix integer overflow in set_timeout
 handler

On 4/15/21 5:12 PM, rentao.bupt@...il.com wrote:
> From: Tao Ren <rentao.bupt@...il.com>
> 
> Fix the time comparison (timeout vs. max_hw_heartbeat_ms) in set_timeout
> handler to avoid potential integer overflow when the supplied timeout is
> greater than aspeed's maximum allowed timeout (4294 seconds).
> 
> Fixes: efa859f7d786 ("watchdog: Add Aspeed watchdog driver")
> Reported-by: Amithash Prasad <amithash@...com>
> Signed-off-by: Tao Ren <rentao.bupt@...il.com>
> ---
>  drivers/watchdog/aspeed_wdt.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index 7e00960651fa..9f77272dc906 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -145,9 +145,8 @@ static int aspeed_wdt_set_timeout(struct watchdog_device *wdd,
>  	struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
>  	u32 actual;
>  
> -	wdd->timeout = timeout;
> -
> -	actual = min(timeout, wdd->max_hw_heartbeat_ms * 1000);
> +	actual = min(timeout, wdd->max_hw_heartbeat_ms / 1000);
> +	wdd->timeout = actual;
>  
>  	writel(actual * WDT_RATE_1MHZ, wdt->base + WDT_RELOAD_VALUE);
>  	writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
> 

If the provided timeout is larger than the supported hardware timeout,
the watchdog core will ping the hardware on behalf of userspace.
The above code would defeat that mechanism for no good reason.

NACK.

Guenter