linux-stable.git/Documentation, branch linux-2.6.32.y

x86-64, espfix: Don't leak bits 31:16 of %esp returning to 16-bit stack

2014-12-13T14:16:08+00:00

commit 3891a04aafd668686239349ea58f3314ea2af86b upstream.

The IRET instruction, when returning to a 16-bit segment, only
restores the bottom 16 bits of the user space stack pointer.  This
causes some 16-bit software to break, but it also leaks kernel state
to user space.  We have a software workaround for that ("espfix") for
the 32-bit kernel, but it relies on a nonzero stack segment base which
is not available in 64-bit mode.

In checkin:

    b3b42ac2cbae x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

we "solved" this by forbidding 16-bit segments on 64-bit kernels, with
the logic that 16-bit support is crippled on 64-bit kernels anyway (no
V86 support), but it turns out that people are doing stuff like
running old Win16 binaries under Wine and expect it to work.

This works around this by creating percpu "ministacks", each of which
is mapped 2^16 times 64K apart.  When we detect that the return SS is
on the LDT, we copy the IRET frame to the ministack and use the
relevant alias to return to userspace.  The ministacks are mapped
readonly, so if IRET faults we promote #GP to #DF which is an IST
vector and thus has its own stack; we then do the fixup in the #DF
handler.

(Making #GP an IST exception would make the msr_safe functions unsafe
in NMI/MC context, and quite possibly have other effects.)

Special thanks to:

- Andy Lutomirski, for the suggestion of using very small stack slots
  and copy (as opposed to map) the IRET frame there, and for the
  suggestion to mark them readonly and let the fault promote to #DF.
- Konrad Wilk for paravirt fixup and testing.
- Borislav Petkov for testing help and useful comments.

Reported-by: Brian Gerst 
Signed-off-by: H. Peter Anvin 
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Cc: Konrad Rzeszutek Wilk 
Cc: Borislav Petkov 
Cc: Andrew Lutomriski 
Cc: Linus Torvalds 
Cc: Dirk Hohndel 
Cc: Arjan van de Ven 
Cc: comex 
Cc: Alexander van Heukelum 
Cc: Boris Ostrovsky 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings 
(cherry picked from 3.2 commit e7836514086d53e0ffaee18d67d85d9477ecdb12)
[wt: backport notes for 2.6.32 differences :
     - use DECLARE_PER_CPU instead of DECLARE_PER_CPU_READ_MOSTLY
     - replace this_cpu_read(foo) with per_cpu(foo, smp_processor_id())
     - replace this_cpu_write(foo,bar) with per_cpu(foo,smp_processor_id())=bar
/wt]
Signed-off-by: Willy Tarreau

Documentation: lzo: document part of the encoding

2014-11-23T09:55:52+00:00

Add a complete description of the LZO format as processed by the
decompressor. I have not found a public specification of this format
hence this analysis, which will be used to better understand the code.

Cc: Willem Pinckaers 
Cc: "Don A. Bailey" 
Cc: stable 
Signed-off-by: Willy Tarreau 
Signed-off-by: Greg Kroah-Hartman 
(cherry picked from commit d98a0526434d27e261f622cf9d2e0028b5ff1a00)
Signed-off-by: Willy Tarreau

x86, random: Verify RDRAND functionality and allow it to be disabled

2012-10-07T21:41:12+00:00

commit 49d859d78c5aeb998b6936fcb5f288f78d713489 upstream.

If the CPU declares that RDRAND is available, go through a guranteed
reseed sequence, and make sure that it is actually working (producing
data.)   If it does not, disable the CPU feature flag.

Allow RDRAND to be disabled on the command line (as opposed to at
compile time) for a user who has special requirements with regards to
random numbers.

Signed-off-by: H. Peter Anvin 
Cc: Matt Mackall 
Cc: Herbert Xu 
Cc: "Theodore Ts'o" 
Signed-off-by: Willy Tarreau

stable: Allow merging of backports for serious user-visible performance issues

2012-10-07T21:37:56+00:00

commit eb3979f64d25120d60b9e761a4c58f70b1a02f86 upstream.

Distribution kernel maintainers routinely backport fixes for users that
were deemed important but not "something critical" as defined by the
rules. To users of these kernels they are very serious and failing to fix
them reduces the value of -stable.

The problem is that the patches fixing these issues are often subtle and
prone to regressions in other ways and need greater care and attention.
To combat this, these "serious" backports should have a higher barrier
to entry.

This patch relaxes the rules to allow a distribution maintainer to merge
to -stable a backported patch or small series that fixes a "serious"
user-visible performance issue. They should include additional information on
the user-visible bug affected and a link to the bugzilla entry if available.
The same rules about the patch being already in mainline still apply.

Signed-off-by: Mel Gorman 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Willy Tarreau

USB: update documentation for usbmon

2012-01-12T19:40:04+00:00

commit d8cae98cddd286e38db1724dda1b0e7b467f9237 upstream.

The documentation for usbmon is out of date; the usbfs "devices" file
now exists in /sys/kernel/debug/usb rather than /proc/bus/usb.  This
patch (as1505) updates the documentation accordingly, and also
mentions that the necessary information can be found by running lsusb.

Signed-off-by: Alan Stern 
CC: Pete Zaitcev 
Signed-off-by: Greg Kroah-Hartman

Documentation: Update stable address

2012-01-12T19:40:00+00:00

commit 2eb7f204db51969ea558802a6601d79c2fb273b9 upstream.

The Japanese/Korean/Chinese versions still need updating.

Also, the stable kernel 2.6.x.y descriptions are out of date
and should be updated as well.

Signed-off-by: Joe Perches 
Signed-off-by: Greg Kroah-Hartman

kbuild: Fix passing -Wno-* options to gcc 4.4+

2011-11-26T17:10:36+00:00

commit 8417da6f2128008c431c7d130af6cd3d9079922e upstream.

Starting with 4.4, gcc will happily accept -Wno- in the
cc-option test and complain later when compiling a file that has some
other warning. This rather unexpected behavior is intentional as per
http://gcc.gnu.org/PR28322, so work around it by testing for support of
the opposite option (without the no-). Introduce a new Makefile function
cc-disable-warning that does this and update two uses of cc-option in
the toplevel Makefile.

Reported-and-tested-by: Stephen Rothwell 
Signed-off-by: Michal Marek 
Signed-off-by: Greg Kroah-Hartman

Remove the old V4L1 v4lgrab.c file

2011-11-26T17:10:34+00:00

commit 55fe25b418640fad04190103274841b2c907bacd upstream.

This example file uses the old V4L1 API. It also doesn't use libv4l.
So, it is completely obsolete. A good example already exists at
v4l-utils (v4l2grab.c):
	http://git.linuxtv.org/v4l-utils.git

Reviewed-by: Hans Verkuil 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Greg Kroah-Hartman

Update email address for stable patch submission

2011-11-07T20:32:23+00:00

commit 5fa224295f0e0358c8bc0e5390702338df889def upstream.

The stable@kernel.org email address has been replaced with the
stable@vger.kernel.org mailing list.  Change the stable kernel rules to
reference the new list instead of the semi-defunct email alias.

Signed-off-by: Josh Boyer 
Signed-off-by: Greg Kroah-Hartman

ALSA: hda - Add support for the new 27 inch IMacs

2011-05-09T22:55:19+00:00

commit 1a5ba2e9fc7999b8de2a71c7e7b9f58d752c05e4 upstream.

With the attached patch I am able to use the sound on a new IMac 27.
What works:

*) Internal speakers
*) Internal microphone
*) Headphone

I don't have an external mic or a SPDIF device to test the rest.

Signed-off-by: Rafael Avila de Espindola 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman