Avoid null pointer dereference if some function is walking through the devs array accessing members of a new virt_dev that is mid allocation.

Add the virt_dev to xhci->devs[i] _after_ the virt_device and all its members are properly allocated.

issue found by KASAN: null-ptr-deref in xhci_find_slot_id_by_port

"Quick analysis suggests that xhci_alloc_virt_device() is not mutex protected. If so, there is a time frame where xhci->devs[slot_id] is set but not fully initialized. Specifically, xhci->devs[i]->udev can be NULL."

Cc: stable stable@vger.kernel.org Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com --- drivers/usb/host/xhci-mem.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index 15f7d42..3a29b32 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -971,10 +971,9 @@ int xhci_alloc_virt_device(struct xhci_hcd *xhci, int slot_id, return 0; }

- xhci->devs[slot_id] = kzalloc(sizeof(*xhci->devs[slot_id]), flags); - if (!xhci->devs[slot_id]) + dev = kzalloc(sizeof(*dev), flags); + if (!dev) return 0; - dev = xhci->devs[slot_id];

/* Allocate the (output) device context that will be used in the HC. */ dev->out_ctx = xhci_alloc_container_ctx(xhci, XHCI_CTX_TYPE_DEVICE, flags); @@ -1015,9 +1014,17 @@ int xhci_alloc_virt_device(struct xhci_hcd *xhci, int slot_id,

trace_xhci_alloc_virt_device(dev);

+ xhci->devs[slot_id] = dev; + return 1; fail: - xhci_free_virt_device(xhci, slot_id); + + if (dev->in_ctx) + xhci_free_container_ctx(xhci, dev->in_ctx); + if (dev->out_ctx) + xhci_free_container_ctx(xhci, dev->out_ctx); + kfree(dev); + return 0; }