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@xxxxxxxxxxxxxxx> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> --- 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; } -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
