linux-stable.git/Documentation, branch v4.1.23

USB: uas: Add a new NO_REPORT_LUNS quirk

2016-04-20T05:13:12+00:00

[ Upstream commit 1363074667a6b7d0507527742ccd7bbed5e3ceaa ]

Add a new NO_REPORT_LUNS quirk and set it for Seagate drives with
an usb-id of: 0bc2:331a, as these will fail to respond to a
REPORT_LUNS command.

Cc: stable@vger.kernel.org
Reported-and-tested-by: David Webb 
Signed-off-by: Hans de Goede 
Acked-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

efi: Make efivarfs entries immutable by default

2016-04-12T02:44:23+00:00

[ Upstream commit ed8b0de5a33d2a2557dce7f9429dca8cb5bc5879 ]

"rm -rf" is bricking some peoples' laptops because of variables being
used to store non-reinitializable firmware driver data that's required
to POST the hardware.

These are 100% bugs, and they need to be fixed, but in the mean time it
shouldn't be easy to *accidentally* brick machines.

We have to have delete working, and picking which variables do and don't
work for deletion is quite intractable, so instead make everything
immutable by default (except for a whitelist), and make tools that
aren't quite so broad-spectrum unset the immutable flag.

Signed-off-by: Peter Jones 
Tested-by: Lee, Chun-Yi 
Acked-by: Matthew Garrett 
Signed-off-by: Matt Fleming 
Signed-off-by: Sasha Levin

KVM: MMU: fix ept=0/pte.u=1/pte.w=0/CR0.WP=0/CR4.SMEP=1/EFER.NX=0 combo

2016-03-22T15:10:34+00:00

[ Upstream commit 844a5fe219cf472060315971e15cbf97674a3324 ]

Yes, all of these are needed. :) This is admittedly a bit odd, but
kvm-unit-tests access.flat tests this if you run it with "-cpu host"
and of course ept=0.

KVM runs the guest with CR0.WP=1, so it must handle supervisor writes
specially when pte.u=1/pte.w=0/CR0.WP=0.  Such writes cause a fault
when U=1 and W=0 in the SPTE, but they must succeed because CR0.WP=0.
When KVM gets the fault, it sets U=0 and W=1 in the shadow PTE and
restarts execution.  This will still cause a user write to fault, while
supervisor writes will succeed.  User reads will fault spuriously now,
and KVM will then flip U and W again in the SPTE (U=1, W=0).  User reads
will be enabled and supervisor writes disabled, going back to the
originary situation where supervisor writes fault spuriously.

When SMEP is in effect, however, U=0 will enable kernel execution of
this page.  To avoid this, KVM also sets NX=1 in the shadow PTE together
with U=0.  If the guest has not enabled NX, the result is a continuous
stream of page faults due to the NX bit being reserved.

The fix is to force EFER.NX=1 even if the CPU is taking care of the EFER
switch.  (All machines with SMEP have the CPU_LOAD_IA32_EFER vm-entry
control, so they do not use user-return notifiers for EFER---if they did,
EFER.NX would be forced to the same value as the host).

There is another bug in the reserved bit check, which I've split to a
separate patch for easier application to stable kernels.

Cc: stable@vger.kernel.org
Cc: Andy Lutomirski 
Reviewed-by: Xiao Guangrong 
Fixes: f6577a5fa15d82217ca73c74cd2dcbc0f6c781dd
Signed-off-by: Paolo Bonzini 
Signed-off-by: Sasha Levin

ARM: OMAP2+: hwmod: Introduce ti,no-idle dt property

2016-03-22T15:10:29+00:00

[ Upstream commit 6327a31a3f875c438ca13058bc4c73f1a752cd8a ]

commit 2e18f5a1bc18e8af7031b3b26efde25307014837 upstream.

Introduce a dt property, ti,no-idle, that prevents an IP to idle at any
point. This is to handle Errata i877, which tells that GMAC clocks
cannot be disabled.

Acked-by: Roger Quadros 
Tested-by: Mugunthan V N 
Signed-off-by: Lokesh Vutla 
Signed-off-by: Sekhar Nori 
Signed-off-by: Dave Gerlach 
Acked-by: Rob Herring 
Signed-off-by: Paul Walmsley 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

net/ipv6: add sysctl option accept_ra_min_hop_limit

2016-03-04T15:25:48+00:00

[ Upstream commit 8013d1d7eafb0589ca766db6b74026f76b7f5cb4 ]

Commit 6fd99094de2b ("ipv6: Don't reduce hop limit for an interface")
disabled accept hop limit from RA if it is smaller than the current hop
limit for security stuff. But this behavior kind of break the RFC definition.

RFC 4861, 6.3.4.  Processing Received Router Advertisements
   A Router Advertisement field (e.g., Cur Hop Limit, Reachable Time,
   and Retrans Timer) may contain a value denoting that it is
   unspecified.  In such cases, the parameter should be ignored and the
   host should continue using whatever value it is already using.

   If the received Cur Hop Limit value is non-zero, the host SHOULD set
   its CurHopLimit variable to the received value.

So add sysctl option accept_ra_min_hop_limit to let user choose the minimum
hop limit value they can accept from RA. And set default to 1 to meet RFC
standards.

Signed-off-by: Hangbin Liu 
Acked-by: YOSHIFUJI Hideaki 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

fs/proc, core/debug: Don't expose absolute kernel addresses via wchan

2015-12-09T19:03:20+00:00

commit b2f73922d119686323f14fbbe46587f863852328 upstream.

So the /proc/PID/stat 'wchan' field (the 30th field, which contains
the absolute kernel address of the kernel function a task is blocked in)
leaks absolute kernel addresses to unprivileged user-space:

        seq_put_decimal_ull(m, ' ', wchan);

The absolute address might also leak via /proc/PID/wchan as well, if
KALLSYMS is turned off or if the symbol lookup fails for some reason:

static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
                          struct pid *pid, struct task_struct *task)
{
        unsigned long wchan;
        char symname[KSYM_NAME_LEN];

        wchan = get_wchan(task);

        if (lookup_symbol_name(wchan, symname) < 0) {
                if (!ptrace_may_access(task, PTRACE_MODE_READ))
                        return 0;
                seq_printf(m, "%lu", wchan);
        } else {
                seq_printf(m, "%s", symname);
        }

        return 0;
}

This isn't ideal, because for example it trivially leaks the KASLR offset
to any local attacker:

  fomalhaut:~> printf "%016lx\n" $(cat /proc/$$/stat | cut -d' ' -f35)
  ffffffff8123b380

Most real-life uses of wchan are symbolic:

  ps -eo pid:10,tid:10,wchan:30,comm

and procps uses /proc/PID/wchan, not the absolute address in /proc/PID/stat:

  triton:~/tip> strace -f ps -eo pid:10,tid:10,wchan:30,comm 2>&1 | grep wchan | tail -1
  open("/proc/30833/wchan", O_RDONLY)     = 6

There's one compatibility quirk here: procps relies on whether the
absolute value is non-zero - and we can provide that functionality
by outputing "0" or "1" depending on whether the task is blocked
(whether there's a wchan address).

These days there appears to be very little legitimate reason
user-space would be interested in  the absolute address. The
absolute address is mostly historic: from the days when we
didn't have kallsyms and user-space procps had to do the
decoding itself via the System.map.

So this patch sets all numeric output to "0" or "1" and keeps only
symbolic output, in /proc/PID/wchan.

( The absolute sleep address can generally still be profiled via
  perf, by tasks with sufficient privileges. )

Reviewed-by: Thomas Gleixner 
Acked-by: Kees Cook 
Acked-by: Linus Torvalds 
Cc: Al Viro 
Cc: Alexander Potapenko 
Cc: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Denys Vlasenko 
Cc: Dmitry Vyukov 
Cc: Kostya Serebryany 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Peter Zijlstra 
Cc: Sasha Levin 
Cc: kasan-dev 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150930135917.GA3285@gmail.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

MFD/OF: document MFD devices and handle simple-mfd

2015-11-09T22:33:39+00:00

commit 22869a9eca4ea5b534538d160b68c7aef44e378a upstream.

This defines a new compatible option for MFD devices "simple-mfd" that will
make the OF core spawn child devices for all subnodes of that MFD device.
It is optional but handy for things like syscon and possibly other
simpler MFD devices.

Since there was no file to put the documentation in, I took this opportunity
to make a small writeup on MFD devices and add the compatible definition
there.

Suggested-by: Lee Jones 
Acked-by: Lee Jones 
Acked-by: Antoine Tenart 
Acked-by: Alexandre Belloni 
Cc: Arnd Bergmann 
Cc: Devicetree 
Cc: Rob Herring 
Cc: Benjamin Herrenschmidt 
Cc: Grant Likely 
Cc: Pawel Moll 
Cc: Mark Rutland 
Cc: Ian Campbell 
Cc: Kumar Gala 
Signed-off-by: Linus Walleij 
Cc: Henrik Juul Pedersen 
Signed-off-by: Greg Kroah-Hartman

docs: update HOWTO for 3.x -> 4.x versioning

2015-10-22T21:43:22+00:00

commit e4144fe5d47c91c92d36cdbd5f31ed8d6e3a57ab upstream.

The HOWTO document needed updating for the new kernel versioning.

Signed-off-by: Mario Carrillo 
Signed-off-by: Jonathan Corbet 
Signed-off-by: Greg Kroah-Hartman

of_mdio: add new DT property 'managed' to specify the PHY management type

2015-10-03T11:49:17+00:00

[ Upstream commit 4cba5c2103657d43d0886e4cff8004d95a3d0def in net-next tree,
  will be pushed to Linus very soon. ]

Currently the PHY management type is selected by the MAC driver arbitrary.
The decision is based on the presence of the "fixed-link" node and on a
will of the driver's authors.
This caused a regression recently, when mvneta driver suddenly started
to use the in-band status for auto-negotiation on fixed links.
It appears the auto-negotiation may not work when expected by the MAC driver.
Sebastien Rannou explains:
<< Yes, I confirm that my HW does not generate an in-band status. AFAIK, it's
a PHY that aggregates 4xSGMIIs to 1xQSGMII ; the MAC side of the PHY (with
inband status) is connected to the switch through QSGMII, and in this context
we are on the media side of the PHY. >>
https://lkml.org/lkml/2015/7/10/206

This patch introduces the new string property 'managed' that allows
the user to set the management type explicitly.
The supported values are:
"auto" - default. Uses either MDIO or nothing, depending on the presence
of the fixed-link node
"in-band-status" - use in-band status

Signed-off-by: Stas Sergeev 

CC: Rob Herring 
CC: Pawel Moll 
CC: Mark Rutland 
CC: Ian Campbell 
CC: Kumar Gala 
CC: Florian Fainelli 
CC: Grant Likely 
CC: devicetree@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: netdev@vger.kernel.org
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

Doc: ABI: testing: configfs-usb-gadget-sourcesink

2015-09-21T17:05:42+00:00

commit 4bc58eb16bb2352854b9c664cc36c1c68d2bfbb7 upstream.

Fix the name of attribute

Signed-off-by: Peter Chen 
Signed-off-by: Felipe Balbi 
Signed-off-by: Greg Kroah-Hartman