linux-kernel - Re: [PATCH] PCI/sysfs: Fix double free 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 for Android: free password hash cracker in your pocket

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

Message-ID: <20221101094004.GD9130@pengutronix.de>
Date:   Tue, 1 Nov 2022 10:40:04 +0100
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>, stable@...r.kernel.org
Subject: Re: [PATCH] PCI/sysfs: Fix double free in error path

Hi Bjorn,

On Fri, Oct 07, 2022 at 08:56:18AM +0200, Sascha Hauer wrote:
> When pci_create_attr() fails then pci_remove_resource_files() is called
> which will iterate over the res_attr[_wc] arrays and frees every non
> NULL entry. To avoid a double free here we have to set the failed entry
> to NULL in pci_create_attr() when freeing it.
> 
> Fixes: b562ec8f74e4 ("PCI: Don't leak memory if sysfs_create_bin_file() fails")
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> Cc: <stable@...r.kernel.org>
> ---
>  drivers/pci/pci-sysfs.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Any input to this one? There's this long unfixed race condition
described here:

https://patchwork.kernel.org/project/linux-pci/patch/20200716110423.xtfyb3n6tn5ixedh@pali/#23547255

And this patch at least prevents my system from crashing when this race
condition occurs.

Sascha

> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index fc804e08e3cb5..a07381d46ddae 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1196,8 +1196,13 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
>  	res_attr->size = pci_resource_len(pdev, num);
>  	res_attr->private = (void *)(unsigned long)num;
>  	retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
> -	if (retval)
> +	if (retval) {
> +		if (write_combine)
> +			pdev->res_attr_wc[num] = NULL;
> +		else
> +			pdev->res_attr[num] = NULL;
>  		kfree(res_attr);
> +	}
>  
>  	return retval;
>  }
> -- 
> 2.30.2
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |