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 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
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-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5d9b70f7d52eb14bb37861c663bae44de9521c35 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -978,10 +978,9 @@ 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);
@@ -1029,9 +1028,17 @@ 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@xxxxxxxxxxxxxxx are
queue-3.18/xhci-don-t-add-a-virt_dev-to-the-devs-array-before-it-s-fully-allocated.patch