[linux] 01/03: USB: fix invalid memory access in hub_activate() (CVE-2015-8816)
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Mon Feb 29 00:42:39 UTC 2016
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benh pushed a commit to branch jessie-security
in repository linux.
commit 226cfb8d990cfde03f908f6a724375d4e8a76f2d
Author: Ben Hutchings <ben at decadent.org.uk>
Date: Sun Feb 28 23:00:08 2016 +0000
USB: fix invalid memory access in hub_activate() (CVE-2015-8816)
---
debian/changelog | 1 +
...fix-invalid-memory-access-in-hub_activate.patch | 88 ++++++++++++++++++++++
debian/patches/series | 1 +
3 files changed, 90 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index 26acea6..454ca6e 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -17,6 +17,7 @@ linux (3.16.7-ckt20-1+deb8u4) UNRELEASED; urgency=medium
* ALSA: usb-audio: avoid freeing umidi object twice (CVE-2016-2384)
* unix: correctly track in-flight fds in sending process user_struct
(regression in 3.16.7-ckt20-1+deb8u3) (CVE-2016-2550)
+ * USB: fix invalid memory access in hub_activate() (CVE-2015-8816)
-- Ben Hutchings <ben at decadent.org.uk> Sat, 23 Jan 2016 22:53:58 +0000
diff --git a/debian/patches/bugfix/all/usb-fix-invalid-memory-access-in-hub_activate.patch b/debian/patches/bugfix/all/usb-fix-invalid-memory-access-in-hub_activate.patch
new file mode 100644
index 0000000..2ee0a07
--- /dev/null
+++ b/debian/patches/bugfix/all/usb-fix-invalid-memory-access-in-hub_activate.patch
@@ -0,0 +1,88 @@
+From: Alan Stern <stern at rowland.harvard.edu>
+Date: Wed, 16 Dec 2015 13:32:38 -0500
+Subject: USB: fix invalid memory access in hub_activate()
+Origin: https://git.kernel.org/linus/e50293ef9775c5f1cf3fcc093037dd6a8c5684ea
+
+Commit 8520f38099cc ("USB: change hub initialization sleeps to
+delayed_work") changed the hub_activate() routine to make part of it
+run in a workqueue. However, the commit failed to take a reference to
+the usb_hub structure or to lock the hub interface while doing so. As
+a result, if a hub is plugged in and quickly unplugged before the work
+routine can run, the routine will try to access memory that has been
+deallocated. Or, if the hub is unplugged while the routine is
+running, the memory may be deallocated while it is in active use.
+
+This patch fixes the problem by taking a reference to the usb_hub at
+the start of hub_activate() and releasing it at the end (when the work
+is finished), and by locking the hub interface while the work routine
+is running. It also adds a check at the start of the routine to see
+if the hub has already been disconnected, in which nothing should be
+done.
+
+Signed-off-by: Alan Stern <stern at rowland.harvard.edu>
+Reported-by: Alexandru Cornea <alexandru.cornea at intel.com>
+Tested-by: Alexandru Cornea <alexandru.cornea at intel.com>
+Fixes: 8520f38099cc ("USB: change hub initialization sleeps to delayed_work")
+Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
+[ luis: backported to 3.16:
+ - Added forward declaration of hub_release() which mainline had with commit
+ 32a6958998c5 ("usb: hub: convert khubd into workqueue") ]
+Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
+---
+ drivers/usb/core/hub.c | 23 ++++++++++++++++++++---
+ 1 file changed, 20 insertions(+), 3 deletions(-)
+
+--- a/drivers/usb/core/hub.c
++++ b/drivers/usb/core/hub.c
+@@ -104,6 +104,7 @@ EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rws
+ #define HUB_DEBOUNCE_STEP 25
+ #define HUB_DEBOUNCE_STABLE 100
+
++static void hub_release(struct kref *kref);
+ static int usb_reset_and_verify_device(struct usb_device *udev);
+
+ static inline char *portspeed(struct usb_hub *hub, int portstatus)
+@@ -1023,10 +1024,20 @@ static void hub_activate(struct usb_hub
+ unsigned delay;
+
+ /* Continue a partial initialization */
+- if (type == HUB_INIT2)
+- goto init2;
+- if (type == HUB_INIT3)
++ if (type == HUB_INIT2 || type == HUB_INIT3) {
++ device_lock(hub->intfdev);
++
++ /* Was the hub disconnected while we were waiting? */
++ if (hub->disconnected) {
++ device_unlock(hub->intfdev);
++ kref_put(&hub->kref, hub_release);
++ return;
++ }
++ if (type == HUB_INIT2)
++ goto init2;
+ goto init3;
++ }
++ kref_get(&hub->kref);
+
+ /* The superspeed hub except for root hub has to use Hub Depth
+ * value as an offset into the route string to locate the bits
+@@ -1224,6 +1235,7 @@ static void hub_activate(struct usb_hub
+ queue_delayed_work(system_power_efficient_wq,
+ &hub->init_work,
+ msecs_to_jiffies(delay));
++ device_unlock(hub->intfdev);
+ return; /* Continues at init3: below */
+ } else {
+ msleep(delay);
+@@ -1245,6 +1257,11 @@ static void hub_activate(struct usb_hub
+ /* Allow autosuspend if it was suppressed */
+ if (type <= HUB_INIT3)
+ usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
++
++ if (type == HUB_INIT2 || type == HUB_INIT3)
++ device_unlock(hub->intfdev);
++
++ kref_put(&hub->kref, hub_release);
+ }
+
+ /* Implement the continuations for the delays above */
diff --git a/debian/patches/series b/debian/patches/series
index f30457b..bc50c5d 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -687,3 +687,4 @@ bugfix/all/af_unix-guard-against-other-sk-in-unix_dgram_sendmsg.patch
bugfix/all/revert-workqueue-make-sure-delayed-work-run-in-local-cpu.patch
bugfix/all/alsa-usb-audio-avoid-freeing-umidi-object-twice.patch
bugfix/all/unix-correctly-track-in-flight-fds-in-sending-process-user_struct.patch
+bugfix/all/usb-fix-invalid-memory-access-in-hub_activate.patch
--
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