linux-toradex.git/arch, branch v3.4.33

efi: Clear EFI_RUNTIME_SERVICES rather than EFI_BOOT by "noefi" boot parameter

2013-02-17T18:49:26+00:00

commit 1de63d60cd5b0d33a812efa455d5933bf1564a51 upstream.

There was a serious problem in samsung-laptop that its platform driver is
designed to run under BIOS and running under EFI can cause the machine to
become bricked or can cause Machine Check Exceptions.

    Discussion about this problem:
    https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
    https://bugzilla.kernel.org/show_bug.cgi?id=47121

    The patches to fix this problem:
    efi: Make 'efi_enabled' a function to query EFI facilities
    83e68189745ad931c2afd45d8ee3303929233e7f

    samsung-laptop: Disable on EFI hardware
    e0094244e41c4d0c7ad69920681972fc45d8ce34

Unfortunately this problem comes back again if users specify "noefi" option.
This parameter clears EFI_BOOT and that driver continues to run even if running
under EFI. Refer to the document, this parameter should clear
EFI_RUNTIME_SERVICES instead.

Documentation/kernel-parameters.txt:
===============================================================================
...
	noefi		[X86] Disable EFI runtime services support.
...
===============================================================================

Documentation/x86/x86_64/uefi.txt:
===============================================================================
...
- If some or all EFI runtime services don't work, you can try following
  kernel command line parameters to turn off some or all EFI runtime
  services.
	noefi		turn off all EFI runtime services
...
===============================================================================

Signed-off-by: Satoru Takeuchi 
Link: http://lkml.kernel.org/r/511C2C04.2070108@jp.fujitsu.com
Cc: Matt Fleming 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86/xen: don't assume %ds is usable in xen_iret for 32-bit PVOPS.

2013-02-17T18:49:26+00:00

commit 13d2b4d11d69a92574a55bfd985cfb0ca77aebdc upstream.

This fixes CVE-2013-0228 / XSA-42

Drew Jones while working on CVE-2013-0190 found that that unprivileged guest user
in 32bit PV guest can use to crash the > guest with the panic like this:

-------------
general protection fault: 0000 [#1] SMP
last sysfs file: /sys/devices/vbd-51712/block/xvda/dev
Modules linked in: sunrpc ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4
iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6
xt_state nf_conntrack ip6table_filter ip6_tables ipv6 xen_netfront ext4
mbcache jbd2 xen_blkfront dm_mirror dm_region_hash dm_log dm_mod [last
unloaded: scsi_wait_scan]

Pid: 1250, comm: r Not tainted 2.6.32-356.el6.i686 #1
EIP: 0061:[] EFLAGS: 00010086 CPU: 0
EIP is at xen_iret+0x12/0x2b
EAX: eb8d0000 EBX: 00000001 ECX: 08049860 EDX: 00000010
ESI: 00000000 EDI: 003d0f00 EBP: b77f8388 ESP: eb8d1fe0
 DS: 0000 ES: 007b FS: 0000 GS: 00e0 SS: 0069
Process r (pid: 1250, ti=eb8d0000 task=c2953550 task.ti=eb8d0000)
Stack:
 00000000 0027f416 00000073 00000206 b77f8364 0000007b 00000000 00000000
Call Trace:
Code: c3 8b 44 24 18 81 4c 24 38 00 02 00 00 8d 64 24 30 e9 03 00 00 00
8d 76 00 f7 44 24 08 00 00 02 80 75 33 50 b8 00 e0 ff ff 21 e0 <8b> 40
10 8b 04 85 a0 f6 ab c0 8b 80 0c b0 b3 c0 f6 44 24 0d 02
EIP: [] xen_iret+0x12/0x2b SS:ESP 0069:eb8d1fe0
general protection fault: 0000 [#2]
---[ end trace ab0d29a492dcd330 ]---
Kernel panic - not syncing: Fatal exception
Pid: 1250, comm: r Tainted: G      D    ---------------
2.6.32-356.el6.i686 #1
Call Trace:
 [] ? panic+0x6e/0x122
 [] ? oops_end+0xbc/0xd0
 [] ? do_general_protection+0x0/0x210
 [] ? error_code+0x73/
-------------

Petr says: "
 I've analysed the bug and I think that xen_iret() cannot cope with
 mangled DS, in this case zeroed out (null selector/descriptor) by either
 xen_failsafe_callback() or RESTORE_REGS because the corresponding LDT
 entry was invalidated by the reproducer. "

Jan took a look at the preliminary patch and came up a fix that solves
this problem:

"This code gets called after all registers other than those handled by
IRET got already restored, hence a null selector in %ds or a non-null
one that got loaded from a code or read-only data descriptor would
cause a kernel mode fault (with the potential of crashing the kernel
as a whole, if panic_on_oops is set)."

The way to fix this is to realize that the we can only relay on the
registers that IRET restores. The two that are guaranteed are the
%cs and %ss as they are always fixed GDT selectors. Also they are
inaccessible from user mode - so they cannot be altered. This is
the approach taken in this patch.

Another alternative option suggested by Jan would be to relay on
the subtle realization that using the %ebp or %esp relative references uses
the %ss segment.  In which case we could switch from using %eax to %ebp and
would not need the %ss over-rides. That would also require one extra
instruction to compensate for the one place where the register is used
as scaled index. However Andrew pointed out that is too subtle and if
further work was to be done in this code-path it could escape folks attention
and lead to accidents.

Reviewed-by: Petr Matousek 
Reported-by: Petr Matousek 
Reviewed-by: Andrew Cooper 
Signed-off-by: Jan Beulich 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Greg Kroah-Hartman

x86/mm: Check if PUD is large when validating a kernel address

2013-02-17T18:49:26+00:00

commit 0ee364eb316348ddf3e0dfcd986f5f13f528f821 upstream.

A user reported the following oops when a backup process reads
/proc/kcore:

 BUG: unable to handle kernel paging request at ffffbb00ff33b000
 IP: [] kern_addr_valid+0xbe/0x110
 [...]

 Call Trace:
  [] read_kcore+0x17a/0x370
  [] proc_reg_read+0x77/0xc0
  [] vfs_read+0xc7/0x130
  [] sys_read+0x53/0xa0
  [] system_call_fastpath+0x16/0x1b

Investigation determined that the bug triggered when reading
system RAM at the 4G mark. On this system, that was the first
address using 1G pages for the virt->phys direct mapping so the
PUD is pointing to a physical address, not a PMD page.

The problem is that the page table walker in kern_addr_valid() is
not checking pud_large() and treats the physical address as if
it was a PMD.  If it happens to look like pmd_none then it'll
silently fail, probably returning zeros instead of real data. If
the data happens to look like a present PMD though, it will be
walked resulting in the oops above.

This patch adds the necessary pud_large() check.

Unfortunately the problem was not readily reproducible and now
they are running the backup program without accessing
/proc/kcore so the patch has not been validated but I think it
makes sense.

Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Reviewed-by: Michal Hocko 
Acked-by: Johannes Weiner 
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20130211145236.GX21389@suse.de
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86/apic: Work around boot failure on HP ProLiant DL980 G7 Server systems

2013-02-17T18:49:25+00:00

commit cb214ede7657db458fd0b2a25ea0b28dbf900ebc upstream.

When a HP ProLiant DL980 G7 Server boots a regular kernel,
there will be intermittent lost interrupts which could
result in a hang or (in extreme cases) data loss.

The reason is that this system only supports x2apic physical
mode, while the kernel boots with a logical-cluster default
setting.

This bug can be worked around by specifying the "x2apic_phys" or
"nox2apic" boot option, but we want to handle this system
without requiring manual workarounds.

The BIOS sets ACPI_FADT_APIC_PHYSICAL in FADT table.
As all apicids are smaller than 255, BIOS need to pass the
control to the OS with xapic mode, according to x2apic-spec,
chapter 2.9.

Current code handle x2apic when BIOS pass with xapic mode
enabled:

When user specifies x2apic_phys, or FADT indicates PHYSICAL:

1. During madt oem check, apic driver is set with xapic logical
   or xapic phys driver at first.

2. enable_IR_x2apic() will enable x2apic_mode.

3. if user specifies x2apic_phys on the boot line, x2apic_phys_probe()
   will install the correct x2apic phys driver and use x2apic phys mode.
   Otherwise it will skip the driver will let x2apic_cluster_probe to
   take over to install x2apic cluster driver (wrong one) even though FADT
   indicates PHYSICAL, because x2apic_phys_probe does not check
   FADT PHYSICAL.

Add checking x2apic_fadt_phys in x2apic_phys_probe() to fix the
problem.

Signed-off-by: Stoney Wang 
[ updated the changelog and simplified the code ]
Signed-off-by: Yinghai Lu 
Link: http://lkml.kernel.org/r/1360263182-16226-1-git-send-email-yinghai@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86: Do not leak kernel page mapping locations

2013-02-17T18:49:25+00:00

commit e575a86fdc50d013bf3ad3aa81d9100e8e6cc60d upstream.

Without this patch, it is trivial to determine kernel page
mappings by examining the error code reported to dmesg[1].
Instead, declare the entire kernel memory space as a violation
of a present page.

Additionally, since show_unhandled_signals is enabled by
default, switch branch hinting to the more realistic
expectation, and unobfuscate the setting of the PF_PROT bit to
improve readability.

[1] http://vulnfactory.org/blog/2013/02/06/a-linux-memory-trick/

Reported-by: Dan Rosenberg 
Suggested-by: Brad Spengler 
Signed-off-by: Kees Cook 
Acked-by: H. Peter Anvin 
Cc: Paul E. McKenney 
Cc: Frederic Weisbecker 
Cc: Eric W. Biederman 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20130207174413.GA12485@www.outflux.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

s390/timer: avoid overflow when programming clock comparator

2013-02-17T18:49:25+00:00

commit d911e03d097bdc01363df5d81c43f69432eb785c upstream.

Since ed4f209 "s390/time: fix sched_clock() overflow" a new helper function
is used to avoid overflows when converting TOD format values to nanosecond
values.
The kvm interrupt code formerly however only worked by accident because of
an overflow. It tried to program a timer that would expire in more than ~29
years. Because of the old TOD-to-nanoseconds overflow bug the real expiry
value however was much smaller, but now it isn't anymore.
This however triggers yet another bug in the function that programs the clock
comparator s390_next_ktime(): if the absolute "expires" value is after 2042
this will result in an overflow and the programmed value is lower than the
current TOD value which immediatly triggers a clock comparator (= timer)
interrupt.
Since the timer isn't expired it will be programmed immediately again and so
on... the result is a dead system.
To fix this simply program the maximum possible value if an overflow is
detected.

Reported-by: Christian Borntraeger 
Tested-by: Christian Borntraeger 
Signed-off-by: Heiko Carstens 
Signed-off-by: Greg Kroah-Hartman

efi: Make 'efi_enabled' a function to query EFI facilities

2013-02-14T18:48:53+00:00

commit 83e68189745ad931c2afd45d8ee3303929233e7f upstream.

Originally 'efi_enabled' indicated whether a kernel was booted from
EFI firmware. Over time its semantics have changed, and it now
indicates whether or not we are booted on an EFI machine with
bit-native firmware, e.g. 64-bit kernel with 64-bit firmware.

The immediate motivation for this patch is the bug report at,

    https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557

which details how running a platform driver on an EFI machine that is
designed to run under BIOS can cause the machine to become
bricked. Also, the following report,

    https://bugzilla.kernel.org/show_bug.cgi?id=47121

details how running said driver can also cause Machine Check
Exceptions. Drivers need a new means of detecting whether they're
running on an EFI machine, as sadly the expression,

    if (!efi_enabled)

hasn't been a sufficient condition for quite some time.

Users actually want to query 'efi_enabled' for different reasons -
what they really want access to is the list of available EFI
facilities.

For instance, the x86 reboot code needs to know whether it can invoke
the ResetSystem() function provided by the EFI runtime services, while
the ACPI OSL code wants to know whether the EFI config tables were
mapped successfully. There are also checks in some of the platform
driver code to simply see if they're running on an EFI machine (which
would make it a bad idea to do BIOS-y things).

This patch is a prereq for the samsung-laptop fix patch.

Signed-off-by: Matt Fleming 
Cc: David Airlie 
Cc: Corentin Chary 
Cc: Matthew Garrett 
Cc: Dave Jiang 
Cc: Olof Johansson 
Cc: Peter Jones 
Cc: Colin Ian King 
Cc: Steve Langasek 
Cc: Tony Luck 
Cc: Konrad Rzeszutek Wilk 
Cc: Rafael J. Wysocki 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86-64: Replace left over sti/cli in ia32 audit exit code

2013-02-11T16:47:18+00:00

commit 40a1ef95da85843696fc3ebe5fce39b0db32669f upstream.

For some reason they didn't get replaced so far by their
paravirt equivalents, resulting in code to be run with
interrupts disabled that doesn't expect so (causing, in the
observed case, a BUG_ON() to trigger) when syscall auditing is
enabled.

David (Cc-ed) came up with an identical fix, so likely this can
be taken to count as an ack from him.

Reported-by: Peter Moody 
Signed-off-by: Jan Beulich 
Cc: David Vrabel 
Cc: Konrad Rzeszutek Wilk 
Link: http://lkml.kernel.org/r/5108E01902000078000BA9C5@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar 
Cc: Konrad Rzeszutek Wilk 
Cc: David Vrabel 
Tested-by: Peter Moody 
Signed-off-by: Greg Kroah-Hartman

x86/Sandy Bridge: Sandy Bridge workaround depends on CONFIG_PCI

2013-02-04T00:24:42+00:00

commit e43b3cec711a61edf047adf6204d542f3a659ef8 upstream.

early_pci_allowed() and read_pci_config_16() are only available if
CONFIG_PCI is defined.

Signed-off-by: H. Peter Anvin 
Cc: Jesse Barnes 
Signed-off-by: Abdallah Chatila

x86, efi: Set runtime_version to the EFI spec revision

2013-02-04T00:24:42+00:00

commit 712ba9e9afc4b3d3d6fa81565ca36fe518915c01 upstream.

efi.runtime_version is erroneously being set to the value of the
vendor's firmware revision instead of that of the implemented EFI
specification. We can't deduce which EFI functions are available based
on the revision of the vendor's firmware since the version scheme is
likely to be unique to each vendor.

What we really need to know is the revision of the implemented EFI
specification, which is available in the EFI System Table header.

Signed-off-by: Matt Fleming 
Cc: Seiji Aguchi 
Cc: Matthew Garrett 
Signed-off-by: Greg Kroah-Hartman