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Xen/x86: don't bail early from clear_foreign_p2m_mapping()
Its sibling (set_foreign_p2m_mapping()) as well as the sibling of its only caller (gnttab_map_refs()) don't clean up after themselves in case of error. Higher level callers are expected to do so. However, in order for that to really clean up any partially set up state, the operation should not terminate upon encountering an entry in unexpected state. It is particularly relevant to notice here that set_foreign_p2m_mapping() would skip setting up a p2m entry if its grant mapping failed, but it would continue to set up further p2m entries as long as their mappings succeeded. Arguably down the road set_foreign_p2m_mapping() may want its page state related WARN_ON() also converted to an error return. This is part of XSA-361. Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
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@ -750,17 +750,15 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
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unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
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unsigned long pfn = page_to_pfn(pages[i]);
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if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
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ret = -EINVAL;
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goto out;
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}
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if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT))
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set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
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else
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ret = -EINVAL;
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}
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if (kunmap_ops)
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ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
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kunmap_ops, count);
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out:
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kunmap_ops, count) ?: ret;
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return ret;
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}
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EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
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