This is a note to let you know that I've just added the patch titled
xhci: Don't add a virt_dev to the devs array before it's fully allocated
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: xhci-don-t-add-a-virt_dev-to-the-devs-array-before-it-s-fully-allocated.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 5d9b70f7d52eb14bb37861c663bae44de9521c35 Mon Sep 17 00:00:00 2001
From: Mathias Nyman mathias.nyman@linux.intel.com Date: Fri, 8 Dec 2017 18:10:05 +0200 Subject: xhci: Don't add a virt_dev to the devs array before it's fully allocated
From: Mathias Nyman mathias.nyman@linux.intel.com
commit 5d9b70f7d52eb14bb37861c663bae44de9521c35 upstream.
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."
Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/host/xhci-mem.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
--- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -1017,10 +1017,9 @@ int xhci_alloc_virt_device(struct xhci_h 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); @@ -1068,9 +1067,17 @@ int xhci_alloc_virt_device(struct xhci_h &xhci->dcbaa->dev_context_ptrs[slot_id], le64_to_cpu(xhci->dcbaa->dev_context_ptrs[slot_id]));
+ 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; }
Patches currently in stable-queue which might be from mathias.nyman@linux.intel.com are
queue-4.4/xhci-don-t-add-a-virt_dev-to-the-devs-array-before-it-s-fully-allocated.patch