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Re: [Qemu-devel] [PATCH] qcow2: Fix alloc_clusters_noref() overflow dete
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From: |
Kevin Wolf |
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Subject: |
Re: [Qemu-devel] [PATCH] qcow2: Fix alloc_clusters_noref() overflow detection |
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Date: |
Mon, 5 May 2014 11:36:15 +0200 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 04.05.2014 um 05:31 hat Max Reitz geschrieben:
> If the very first allocation has a length of 0, the free_cluster_index
> is still 0 after the for loop, which means that subtracting one from it
> will underflow and signal an invalid range of clusters by returning
> -EFBIG. However, there is no such range, as its length is 0.
>
> Fix this by preventing underflows on free_cluster_index during the
> check.
>
> Signed-off-by: Max Reitz <address@hidden>
Heh, I wondered about this when I reviewed that other patch, and came to
the conclusion that it probably doesn't happen. Did you find a case
where it does happen in fact?
Anyway, this can't hurt:
Reviewed-by: Kevin Wolf <address@hidden>