From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Russell King <linux@armlinux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH] arm: dma-mapping: fix potential endless loop in __dma_page_dev_to_cpu()
Date: Wed, 9 Aug 2023 19:05:04 +0200 [thread overview]
Message-ID: <ab061a6b-2aeb-fb62-3dd0-a20059ff10ac@samsung.com> (raw)
In-Reply-To: <ZNEagJ6rVDwBKUdr@casper.infradead.org>
Hi,
On 07.08.2023 18:23, Matthew Wilcox wrote:
> On Mon, Aug 07, 2023 at 05:26:57PM +0200, Marek Szyprowski wrote:
>> It is possible that the folio_size() of the next folio returns zero, so
> What? How can folio_size() return zero?
>
> return PAGE_SIZE << folio_order(folio);
>
> It is a minimum of PAGE_SIZE.
Well, the folio_order() on that next folio returns 255, so folio_size()
overflows to zero. However, the main source of this issue is relying on
the properties of the folio beyond the requested sync region.
> ...
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
WARNING: multiple messages have this Message-ID (diff)
From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Russell King <linux@armlinux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH] arm: dma-mapping: fix potential endless loop in __dma_page_dev_to_cpu()
Date: Wed, 9 Aug 2023 19:05:04 +0200 [thread overview]
Message-ID: <ab061a6b-2aeb-fb62-3dd0-a20059ff10ac@samsung.com> (raw)
In-Reply-To: <ZNEagJ6rVDwBKUdr@casper.infradead.org>
Hi,
On 07.08.2023 18:23, Matthew Wilcox wrote:
> On Mon, Aug 07, 2023 at 05:26:57PM +0200, Marek Szyprowski wrote:
>> It is possible that the folio_size() of the next folio returns zero, so
> What? How can folio_size() return zero?
>
> return PAGE_SIZE << folio_order(folio);
>
> It is a minimum of PAGE_SIZE.
Well, the folio_order() on that next folio returns 255, so folio_size()
overflows to zero. However, the main source of this issue is relying on
the properties of the folio beyond the requested sync region.
> ...
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-08-09 17:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20230807152704eucas1p1bbe08af4559a7d2984198fe8ba487a2e@eucas1p1.samsung.com>
2023-08-07 15:26 ` [PATCH] arm: dma-mapping: fix potential endless loop in __dma_page_dev_to_cpu() Marek Szyprowski
2023-08-07 15:26 ` Marek Szyprowski
2023-08-07 16:23 ` Matthew Wilcox
2023-08-07 16:23 ` Matthew Wilcox
2023-08-09 17:05 ` Marek Szyprowski [this message]
2023-08-09 17:05 ` Marek Szyprowski
2023-08-07 22:14 ` Matthew Wilcox
2023-08-07 22:14 ` Matthew Wilcox
2023-08-07 22:46 ` Russell King (Oracle)
2023-08-07 22:46 ` Russell King (Oracle)
2023-08-09 19:38 ` Matthew Wilcox
2023-08-09 19:38 ` Matthew Wilcox
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