34 lines
1.4 KiB
Diff
34 lines
1.4 KiB
Diff
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References: bnc#842515 CVE-2013-4375 XSA-71
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xen_disk: mark ioreq as mapped before unmapping in error case
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Commit c6961b7d ("xen_disk: use bdrv_aio_flush instead of bdrv_flush")
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modified the semantics of ioreq_{un,}map so that they are idempotent if
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called when they're not needed (ie., twice in a row). However, it neglected
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to handle the case where batch mapping is not being used (the default), and
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one of the grants fails to map. In this case, ioreq_unmap will be called to
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unwind and unmap any mappings already performed, but ioreq_unmap simply
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returns due to the aforementioned change (the ioreq has not already been
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marked as mapped).
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The frontend user can therefore force xen_disk to leak grant mappings, a
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per-backend-domain limited resource.
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Fix by marking the ioreq as mapped before calling ioreq_unmap in this
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situation.
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This is XSA-71 / CVE-2013-4375
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Signed-off-by: Matthew Daley <mattjd@gmail.com>
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--- a/tools/qemu-xen-dir-remote/hw/xen_disk.c
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+++ b/tools/qemu-xen-dir-remote/hw/xen_disk.c
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@@ -406,6 +406,7 @@ static int ioreq_map(struct ioreq *ioreq
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xen_be_printf(&ioreq->blkdev->xendev, 0,
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"can't map grant ref %d (%s, %d maps)\n",
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refs[i], strerror(errno), ioreq->blkdev->cnt_map);
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+ ioreq->mapped = 1;
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ioreq_unmap(ioreq);
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return -1;
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}
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