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  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]
Date:   Fri, 25 Mar 2022 18:42:19 +0000
From:   Robin Murphy <>
To:     Toke Høiland-Jørgensen <>,
        Christoph Hellwig <>,
        Halil Pasic <>
Cc:     Linus Torvalds <>,
        Oleksandr Natalenko <>,
        Marek Szyprowski <>,
        Kalle Valo <>,
        "David S. Miller" <>,
        Jakub Kicinski <>,
        Paolo Abeni <>,
        Olha Cherevyk <>,
        iommu <>,
        linux-wireless <>,
        Netdev <>,
        Linux Kernel Mailing List <>,
        Greg Kroah-Hartman <>,
        stable <>
Subject: Re: [REGRESSION] Recent swiotlb DMA_FROM_DEVICE fixes break
 ath9k-based AP

On 2022-03-25 18:15, Toke Høiland-Jørgensen wrote:
> Christoph Hellwig <> writes:
>> On Thu, Mar 24, 2022 at 07:02:16PM +0100, Halil Pasic wrote:
>>>> If
>>>> ddbd89deb7d3 alone turns out to work OK then I'd be inclined to try a
>>>> partial revert of just that one hunk.
>>> I'm not against being pragmatic and doing the partial revert. But as
>>> explained above, I do believe for correctness of swiotlb we ultimately
>>> do need that change. So if the revert is the short term solution,
>>> what should be our mid-term road-map?
>> Unless I'm misunderstanding this thread we found the bug in ath9k
>> and have a fix for that now?
> According to Maxim's comment on the other subthread, that ath9k patch
> wouldn't work on all platforms (and constitutes a bit of a violation of
> the DMA API ownership abstraction). So not quite, I think?

Indeed, it would potentially stand to pose the same problem as the 
SWIOTLB change, but on the scale of individual cache lines touched by 
ath9k_hw_process_rxdesc_edma() rather than the whole buffer. However, 
that might represent a less severe impact on a smaller number of users 
(maybe the MIPS systems? I'm not sure...) so perhaps it's an acceptable 
tourniquet? Note that the current code is already a violation of the DMA 
API (because the device keeps writing even when it doesn't have 
ownership), so there's not a very strong argument in that regard.


Powered by blists - more mailing lists