On systems that hide the PCI bridge device corresponding to a PCIe RC port

we may end up passing a NULL pointer to pcie_get_speed_cap().  Handle this
by returning PCI_SPEED_UNKNOWN instead of dereferencing a null-pointer.

ok jsg@

diff --git a/sys/dev/pci/drm/drm_linux.c b/sys/dev/pci/drm/drm_linux.c
index 1fc4db1..e478bbd 100644 (file)
--- a/sys/dev/pci/drm/drm_linux.c
+++ b/sys/dev/pci/drm/drm_linux.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: drm_linux.c,v 1.78 2021/02/14 03:42:55 jsg Exp $      */
+/*     $OpenBSD: drm_linux.c,v 1.79 2021/04/11 15:30:51 kettenis Exp $ */
 /*
  * Copyright (c) 2013 Jonathan Gray <jsg@openbsd.org>
  * Copyright (c) 2015, 2016 Mark Kettenis <kettenis@openbsd.org>
@@ -1760,14 +1760,20 @@ get_dma_buf(struct dma_buf *dmabuf)
 enum pci_bus_speed
 pcie_get_speed_cap(struct pci_dev *pdev)
 {
-       pci_chipset_tag_t       pc = pdev->pc;
-       pcitag_t                tag = pdev->tag;
+       pci_chipset_tag_t       pc;
+       pcitag_t                tag;
        int                     pos ;
        pcireg_t                xcap, lnkcap = 0, lnkcap2 = 0;
        pcireg_t                id;
        enum pci_bus_speed      cap = PCI_SPEED_UNKNOWN;
        int                     bus, device, function;
 
+       if (pdev == NULL)
+               return PCI_SPEED_UNKNOWN;
+
+       pc = pdev->pc;
+       tag = pdev->tag;
+
        if (!pci_get_capability(pc, tag, PCI_CAP_PCIEXPRESS,
            &pos, NULL)) 
                return PCI_SPEED_UNKNOWN;