[PATCH 4.9 133/206] PCI/MSI: Check for NULL affinity mask in pci_irq_get_affinity()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Beulich <JBeulich@xxxxxxxx>

commit d1d111e073840b8dbc1ae90ba3fc274736451bdc upstream.

If msi_setup_entry() fails to allocate an affinity mask, it logs a message
but continues on and allocates an MSI entry with entry->affinity == NULL.

Check for this case in pci_irq_get_affinity() so we don't try to
dereference a NULL pointer.

[bhelgaas: changelog]
Fixes: ee8d41e53efe "pci/msi: Retrieve affinity for a vector"
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/pci/msi.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1294,7 +1294,8 @@ const struct cpumask *pci_irq_get_affini
 	} else if (dev->msi_enabled) {
 		struct msi_desc *entry = first_pci_msi_entry(dev);
 
-		if (WARN_ON_ONCE(!entry || nr >= entry->nvec_used))
+		if (WARN_ON_ONCE(!entry || !entry->affinity ||
+				 nr >= entry->nvec_used))
 			return NULL;
 
 		return &entry->affinity[nr];