linux-kernel - Re: [PATCH] misc: fastrpc: Fix double free of 'buf' in error path

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: <ZGgIw3rzigqI92BO@dev-linux.lan>
Date:   Fri, 19 May 2023 16:39:47 -0700
From:   Sukrut Bellary <sukrut.bellary@...ux.com>
To:     Dan Carpenter <dan.carpenter@...aro.org>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Abel Vesa <abel.vesa@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] misc: fastrpc: Fix double free of 'buf' in error path

On Fri, May 19, 2023 at 01:58:10PM +0300, Dan Carpenter wrote:
> This is unrelated but I was looking through the driver and I notice
> a bunch of code doing:
> 
> grep 'return ret ?' drivers/firmware/ -R
> 
> 	return ret ? : res.result[0];
> 
> "ret" here is a kernel error code, and res.result[0] is a firmware
> error code.  Mixing error codes is a dangerous thing.  I was reviewing
> some of the callers and the firmware error code gets passed quite far
> back into the kernel to where we would only expect kernel error codes.
> 
> Presumably the firmware is returning positive error codes?  To be honest,
> I am just guessing.  It's better to convert custom error codes to kernel
> error codes as soon as possible.  I am just guessing.  Sukrut, do you
> think you could take a look?  If the callers do not differentiate
> between negative kernel error codes and positive custom error codes then
> probably just do:
> 
> 	if (res.result[0])
> 		ret = -EIO; // -EINVAL?
> 	return ret;
> 

Thanks, Dan, for sharing your findings.
Yes, sure, I will take a look.

Regards,
Sukrut Bellary

> Also there are a couple places which do:
> 
> 	return ret ? false : !!res.result[0];
> 
> Here true means success and false means failure.  So the !! converts
> a firmware error code to true when it should be false so that's a bug.
> Quadruple negatives are confusing...  It should be:
> 
> 	if (ret || res.result[0])
> 		return false;
> 	return true;
> 
> regards,
> dan carpenter
>