linux-stable.git/Documentation/kernel-parameters.txt, branch linux-4.1.y

x86/paravirt: Remove 'noreplace-paravirt' cmdline option

2018-03-04T15:28:33+00:00

[ Upstream commit 12c69f1e94c89d40696e83804dd2f0965b5250cd ]

The 'noreplace-paravirt' option disables paravirt patching, leaving the
original pv indirect calls in place.

That's highly incompatible with retpolines, unless we want to uglify
paravirt even further and convert the paravirt calls to retpolines.

As far as I can tell, the option doesn't seem to be useful for much
other than introducing surprising corner cases and making the kernel
vulnerable to Spectre v2.  It was probably a debug option from the early
paravirt days.  So just remove it.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Juergen Gross 
Cc: Andrea Arcangeli 
Cc: Peter Zijlstra 
Cc: Andi Kleen 
Cc: Ashok Raj 
Cc: Greg KH 
Cc: Jun Nakajima 
Cc: Tim Chen 
Cc: Rusty Russell 
Cc: Dave Hansen 
Cc: Asit Mallick 
Cc: Andy Lutomirski 
Cc: Linus Torvalds 
Cc: Jason Baron 
Cc: Paolo Bonzini 
Cc: Alok Kataria 
Cc: Arjan Van De Ven 
Cc: David Woodhouse 
Cc: Dan Williams 
Link: https://lkml.kernel.org/r/20180131041333.2x6blhxirc2kclrq@treble
Signed-off-by: Sasha Levin

x86/mm: Add the 'nopcid' boot option to turn off PCID

2018-03-01T00:32:18+00:00

[ Upstream commit 0790c9aad84901ca1bdc14746175549c8b5da215 ]

The parameter is only present on x86_64 systems to save a few bytes,
as PCID is always disabled on x86_32.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Nadav Amit 
Reviewed-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
Cc: Andrew Morton 
Cc: Arjan van de Ven 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: Linus Torvalds 
Cc: Mel Gorman 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/8bbb2e65bcd249a5f18bfb8128b4689f08ac2b60.1498751203.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

x86/mm: Add a 'noinvpcid' boot option to turn off INVPCID

2018-03-01T00:32:12+00:00

[ Upstream commit d12a72b844a49d4162f24cefdab30bed3f86730e ]

This adds a chicken bit to turn off INVPCID in case something goes
wrong.  It's an early_param() because we do TLB flushes before we
parse __setup() parameters.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Borislav Petkov 
Cc: Andrew Morton 
Cc: Andrey Ryabinin 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Luis R. Rodriguez 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Toshi Kani 
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/f586317ed1bc2b87aee652267e515b90051af385.1454096309.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

mm: larger stack guard gap, between vmas

2017-06-28T22:57:15+00:00

[ Upstream commit 1be7107fbe18eed3e319a6c3e83c78254b693acb ]

Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.

This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.

Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.

One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications.  For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).

Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.

Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.

Original-patch-by: Oleg Nesterov 
Original-patch-by: Michal Hocko 
Signed-off-by: Hugh Dickins 
Acked-by: Michal Hocko 
Tested-by: Helge Deller  # parisc
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

x86/platform/goldfish: Prevent unconditional loading

2017-05-17T19:06:59+00:00

[ Upstream commit 47512cfd0d7a8bd6ab71d01cd89fca19eb2093eb ]

The goldfish platform code registers the platform device unconditionally
which causes havoc in several ways if the goldfish_pdev_bus driver is
enabled:

 - Access to the hardcoded physical memory region, which is either not
   available or contains stuff which is completely unrelated.

 - Prevents that the interrupt of the serial port can be requested

 - In case of a spurious interrupt it goes into a infinite loop in the
   interrupt handler of the pdev_bus driver (which needs to be fixed
   seperately).

Add a 'goldfish' command line option to make the registration opt-in when
the platform is compiled in.

I'm seriously grumpy about this engineering trainwreck, which has seven
SOBs from Intel developers for 50 lines of code. And none of them figured
out that this is broken. Impressive fail!

Fixes: ddd70cf93d78 ("goldfish: platform device for x86")
Reported-by: Gabriel C 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Acked-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

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

ima: update builtin policies

2015-08-03T16:29:12+00:00

commit 24fd03c87695a76f0517df42a37e51b1597d2c8a upstream.

This patch defines a builtin measurement policy "tcb", similar to the
existing "ima_tcb", but with additional rules to also measure files
based on the effective uid and to measure files opened with the "read"
mode bit set (eg. read, read-write).

Changing the builtin "ima_tcb" policy could potentially break existing
users.  Instead of defining a new separate boot command line option each
time the builtin measurement policy is modified, this patch defines a
single generic boot command line option "ima_policy=" to specify the
builtin policy and deprecates the use of the builtin ima_tcb policy.

[The "ima_policy=" boot command line option is based on Roberto Sassu's
"ima: added new policy type exec" patch.]

Signed-off-by: Mimi Zohar 
Signed-off-by: Dr. Greg Wettstein 
Signed-off-by: Greg Kroah-Hartman

Merge git://git.infradead.org/intel-iommu

2015-06-12T18:28:57+00:00

Pull VT-d hardware workarounds from David Woodhouse:
 "This contains a workaround for hardware issues which I *thought* were
  never going to be seen on production hardware.  I'm glad I checked
  that before the 4.1 release...

  Firstly, PASID support is so broken on existing chips that we're just
  going to declare the old capability bit 28 as 'reserved' and change
  the VT-d spec to move PASID support to another bit.  So any existing
  hardware doesn't support SVM; it only sets that (now) meaningless bit
  28.

  That patch *wasn't* imperative for 4.1 because we don't have PASID
  support yet.  But *even* the extended context tables are broken — if
  you just enable the wider tables and use none of the new bits in them,
  which is precisely what 4.1 does, you find that translations don't
  work.  It's this problem which I thought was caught in time to be
  fixed before production, but wasn't.

  To avoid triggering this issue, we now *only* enable the extended
  context tables on hardware which also advertises "we have PASID
  support and we actually tested it this time" with the new PASID
  feature bit.

  In addition, I've added an 'intel_iommu=ecs_off' command line
  parameter to allow us to disable it manually if we need to"

* git://git.infradead.org/intel-iommu:
  iommu/vt-d: Only enable extended context tables if PASID is supported
  iommu/vt-d: Change PASID support to bit 40 of Extended Capability Register

iommu/vt-d: Only enable extended context tables if PASID is supported

2015-06-12T10:31:25+00:00

Although the extended tables are theoretically a completely orthogonal
feature to PASID and anything else that *uses* the newly-available bits,
some of the early hardware has problems even when all we do is enable
them and use only the same bits that were in the old context tables.

For now, there's no motivation to support extended tables unless we're
going to use PASID support to do SVM. So just don't use them unless
PASID support is advertised too. Also add a command-line bailout just in
case later chips also have issues.

The equivalent problem for PASID support has already been fixed with the
upcoming VT-d spec update and commit bd00c606a ("iommu/vt-d: Change
PASID support to bit 40 of Extended Capability Register"), because the
problematic platforms use the old definition of the PASID-capable bit,
which is now marked as reserved and meaningless.

So with this change, we'll magically start using ECS again only when we
see the new hardware advertising "hey, we have PASID support and we
actually tested it this time" on bit 40.

The VT-d hardware architect has promised that we are not going to have
any reason to support ECS *without* PASID any time soon, and he'll make
sure he checks with us before changing that.

In the future, if hypothetical new features also use new bits in the
context tables and can be seen on implementations *without* PASID support,
we might need to add their feature bits to the ecs_enabled() macro.

Signed-off-by: David Woodhouse

uas: Add US_FL_MAX_SECTORS_240 flag

2015-04-28T10:48:57+00:00

The usb-storage driver sets max_sectors = 240 in its scsi-host template,
for uas we do not want to do that for all devices, but testing has shown
that some devices need it.

This commit adds a US_FL_MAX_SECTORS_240 flag for such devices, and
implements support for it in uas.c, while at it it also adds support
for US_FL_MAX_SECTORS_64 to uas.c.

Cc: stable@vger.kernel.org # 3.16
Signed-off-by: Hans de Goede 
Acked-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman