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 <sta...@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.ny...@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;
}
--
2.7.4
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