From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] iommu/iova: Sort out rbtree limit_pfn handling
Date: Wed, 17 May 2017 16:07:06 +0200 [thread overview]
Message-ID: <20170517140706.GD1912@8bytes.org> (raw)
In-Reply-To: <2f161f6406fd33ea979f6b128f36bb8ac9044d06.1494933782.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
On Tue, May 16, 2017 at 12:26:48PM +0100, Robin Murphy wrote:
> When walking the rbtree, the fact that iovad->start_pfn and limit_pfn
> are both inclusive limits creates an ambiguity once limit_pfn reaches
> the bottom of the address space and they overlap. Commit 5016bdb796b3
> ("iommu/iova: Fix underflow bug in __alloc_and_insert_iova_range") fixed
> the worst side-effect of this, that of underflow wraparound leading to
> bogus allocations, but the remaining fallout is that any attempt to
> allocate start_pfn itself erroneously fails.
>
> The cleanest way to resolve the ambiguity is to simply make limit_pfn an
> exclusive limit when inside the guts of the rbtree. Since we're working
> with PFNs, representing one past the top of the address space is always
> possible without fear of overflow, and elsewhere it just makes life a
> little more straightforward.
>
> Reported-by: Aaron Sierra <asierra-AQeFf1F/bRxBDgjK7y7TUQ@public.gmane.org>
> Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
Applied, thanks.
WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
asierra@xes-inc.com, nwatters@codeaurora.org
Subject: Re: [PATCH] iommu/iova: Sort out rbtree limit_pfn handling
Date: Wed, 17 May 2017 16:07:06 +0200 [thread overview]
Message-ID: <20170517140706.GD1912@8bytes.org> (raw)
In-Reply-To: <2f161f6406fd33ea979f6b128f36bb8ac9044d06.1494933782.git.robin.murphy@arm.com>
On Tue, May 16, 2017 at 12:26:48PM +0100, Robin Murphy wrote:
> When walking the rbtree, the fact that iovad->start_pfn and limit_pfn
> are both inclusive limits creates an ambiguity once limit_pfn reaches
> the bottom of the address space and they overlap. Commit 5016bdb796b3
> ("iommu/iova: Fix underflow bug in __alloc_and_insert_iova_range") fixed
> the worst side-effect of this, that of underflow wraparound leading to
> bogus allocations, but the remaining fallout is that any attempt to
> allocate start_pfn itself erroneously fails.
>
> The cleanest way to resolve the ambiguity is to simply make limit_pfn an
> exclusive limit when inside the guts of the rbtree. Since we're working
> with PFNs, representing one past the top of the address space is always
> possible without fear of overflow, and elsewhere it just makes life a
> little more straightforward.
>
> Reported-by: Aaron Sierra <asierra@xes-inc.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Applied, thanks.
next prev parent reply other threads:[~2017-05-17 14:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-16 11:26 [PATCH] iommu/iova: Sort out rbtree limit_pfn handling Robin Murphy
[not found] ` <2f161f6406fd33ea979f6b128f36bb8ac9044d06.1494933782.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2017-05-16 13:42 ` Aaron Sierra
2017-05-16 13:42 ` Aaron Sierra
2017-05-17 14:07 ` Joerg Roedel [this message]
2017-05-17 14:07 ` Joerg Roedel
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