44 lines
1.4 KiB
Diff
44 lines
1.4 KiB
Diff
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References: bnc#849667 CVE-2013-4553 XSA-74
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x86: restrict XEN_DOMCTL_getmemlist
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Coverity ID 1055652
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(See the code comment.)
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This is CVE-2013-4553 / XSA-74.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
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Reviewed-by: Tim Deegan <tim@xen.org>
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--- a/xen/arch/x86/domctl.c
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+++ b/xen/arch/x86/domctl.c
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@@ -329,6 +329,26 @@ long arch_do_domctl(
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break;
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}
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+ /*
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+ * XSA-74: This sub-hypercall is broken in several ways:
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+ * - lock order inversion (p2m locks inside page_alloc_lock)
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+ * - no preemption on huge max_pfns input
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+ * - not (re-)checking d->is_dying with page_alloc_lock held
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+ * - not honoring start_pfn input (which libxc also doesn't set)
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+ * Additionally it is rather useless, as the result is stale by the
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+ * time the caller gets to look at it.
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+ * As it only has a single, non-production consumer (xen-mceinj),
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+ * rather than trying to fix it we restrict it for the time being.
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+ */
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+ if ( /* No nested locks inside copy_to_guest_offset(). */
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+ paging_mode_external(current->domain) ||
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+ /* Arbitrary limit capping processing time. */
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+ max_pfns > GB(4) / PAGE_SIZE )
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+ {
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+ ret = -EOPNOTSUPP;
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+ break;
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+ }
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+
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spin_lock(&d->page_alloc_lock);
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ret = i = 0;
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