xen_disk: mark ioreq as mapped before unmapping in error case
Commit 4472beae modified the semantics of ioreq_{un,}map so that they are idempotent if called when they're not needed (ie., twice in a row). However, it neglected to handle the case where batch mapping is not being used (the default), and one of the grants fails to map. In this case, ioreq_unmap will be called to unwind and unmap any mappings already performed, but ioreq_unmap simply returns due to the aforementioned change (the ioreq has not already been marked as mapped). The frontend user can therefore force xen_disk to leak grant mappings, a per-domain limited resource. Fix by marking the ioreq as mapped before calling ioreq_unmap in this situation. Signed-off-by: Matthew Daley <mattjd@gmail.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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@ -405,6 +405,7 @@ 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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