linux-kernel - Re: [SHDCI] Heavy (thousands) DMA leaks

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: <55BF36D6.4080504@suse.cz>
Date:	Mon, 3 Aug 2015 11:39:34 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Chen Bough <Haibo.Chen@...escale.com>
Cc:	Ulf Hansson <ulf.hansson@...aro.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [SHDCI] Heavy (thousands) DMA leaks

Hi,

On 08/03/2015, 11:30 AM, Chen Bough wrote:
> I carefully review my patch, all the DMA memory mapped in sdhci_pre_req() is unmapped in sdhci_post_req.

I suspect 'host_cookie' or 'next' handling is bad somewhere. But I don't
know...

> Can you provide the method of your testing DMA leaks?

boot kernel with CONFIG_DMA_API_DEBUG
insert the card
mount it
rsync from the card ~200 MB
umount it
unload the sdhci driver
the leak warning is reported

I am not sure whether suspend-resume is needed after the first step.

> You said over 4000 leaked mappings during one card transfer, if true, 
> We can't map any dma memory after some sd transfer, do you meet this?

Yes, I see:
sdhci-pci 0000:02:00.0: swiotlb buffer is full (sz: 65536 bytes)
after some time. The driver falls back to non-DMA transfers after that.
It also generates a warning about that:
WARNING: CPU: 0 PID: 0 at drivers/mmc/host/sdhci.c:857
sdhci_prepare_data+0x8ec/0x900 [sdhci]()

thanks,
-- 
js
suse labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/