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authorMathias Nyman <mathias.nyman@linux.intel.com>2017-12-08 18:10:05 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-12-08 18:26:34 +0100
commit5d9b70f7d52eb14bb37861c663bae44de9521c35 (patch)
parentbe6123df1ea8f01ee2f896a16c2b7be3e4557a5a (diff)
xhci: Don't add a virt_dev to the devs array before it's fully allocated
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 11 insertions, 4 deletions
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 15f7d422885f..3a29b32a3bd0 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,
+ xhci->devs[slot_id] = dev;
return 1;
- 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;