From: Jan Beulich jbeulich@suse.com
commit a35f2ef3b7376bfd0a57f7844bd7454389aae1fc upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/xen/p2m.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)
--- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -763,17 +763,15 @@ int clear_foreign_p2m_mapping(struct gnt unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i])); unsigned long pfn = page_to_pfn(pages[i]);
- if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) { + if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT)) + set_phys_to_machine(pfn, INVALID_P2M_ENTRY); + else ret = -EINVAL; - goto out; - } - - set_phys_to_machine(pfn, INVALID_P2M_ENTRY); } if (kunmap_ops) ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, - kunmap_ops, count); -out: + kunmap_ops, count) ?: ret; + return ret; } EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);