From: Mathias Nyman Date: Wed, 4 Mar 2026 22:36:39 +0000 (+0200) Subject: xhci: Fix NULL pointer dereference when reading portli debugfs files X-Git-Tag: v7.0-rc4~14^2~14 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ae4ff9dead5efa2025eddfcdb29411432bf40a7c;p=thirdparty%2Fkernel%2Fstable.git xhci: Fix NULL pointer dereference when reading portli debugfs files Michal reported and debgged a NULL pointer dereference bug in the recently added portli debugfs files Oops is caused when there are more port registers counted in xhci->max_ports than ports reported by Supported Protocol capabilities. This is possible if max_ports is more than maximum port number, or if there are gaps between ports of different speeds the 'Supported Protocol' capabilities. In such cases port->rhub will be NULL so we can't reach xhci behind it. Add an explicit NULL check for this case, and print portli in hex without dereferencing port->rhub. Reported-by: Michal Pecio Closes: https://lore.kernel.org/linux-usb/20260304103856.48b785fd.michal.pecio@gmail.com Fixes: 384c57ec7205 ("usb: xhci: Add debugfs support for xHCI Port Link Info (PORTLI) register.") Cc: stable@vger.kernel.org Signed-off-by: Mathias Nyman Link: https://patch.msgid.link/20260304223639.3882398-4-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/host/xhci-debugfs.c b/drivers/usb/host/xhci-debugfs.c index 890fc5e892f1b..ade178ab34a78 100644 --- a/drivers/usb/host/xhci-debugfs.c +++ b/drivers/usb/host/xhci-debugfs.c @@ -386,11 +386,19 @@ static const struct file_operations port_fops = { static int xhci_portli_show(struct seq_file *s, void *unused) { struct xhci_port *port = s->private; - struct xhci_hcd *xhci = hcd_to_xhci(port->rhub->hcd); + struct xhci_hcd *xhci; u32 portli; portli = readl(&port->port_reg->portli); + /* port without protocol capability isn't added to a roothub */ + if (!port->rhub) { + seq_printf(s, "0x%08x\n", portli); + return 0; + } + + xhci = hcd_to_xhci(port->rhub->hcd); + /* PORTLI fields are valid if port is a USB3 or eUSB2V2 port */ if (port->rhub == &xhci->usb3_rhub) seq_printf(s, "0x%08x LEC=%u RLC=%u TLC=%u\n", portli,