linux-stable.git/Documentation/kernel-parameters.txt, branch v3.16.52 Linux kernel stable tree mm: larger stack guard gap, between vmas 2017-07-02T16:13:02+00:00 Hugh Dickins hughd@google.com 2017-06-19T11:03:24+00:00 978b8aa1646d4e023edd121c7f1b8f938ccb813d commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream. 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 <oleg@redhat.com> Original-patch-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Tested-by: Helge Deller <deller@gmx.de> # parisc Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [Hugh Dickins: Backported to 3.16] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.

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 <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Hugh Dickins: Backported to 3.16]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
x86/platform/goldfish: Prevent unconditional loading 2017-06-05T20:17:09+00:00 Thomas Gleixner tglx@linutronix.de 2017-02-15T10:11:50+00:00 843fd93d1e83adb30a7bc39d5c89f680247ba82e commit 47512cfd0d7a8bd6ab71d01cd89fca19eb2093eb upstream. 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 <nix.or.die@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 47512cfd0d7a8bd6ab71d01cd89fca19eb2093eb upstream.

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 <nix.or.die@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
USB: uas: Add a new NO_REPORT_LUNS quirk 2016-06-15T20:29:23+00:00 Hans de Goede hdegoede@redhat.com 2016-04-12T10:27:09+00:00 4bba2ce7c1e18eef89b24f98b47375cb1e80ebe8 commit 1363074667a6b7d0507527742ccd7bbed5e3ceaa upstream. 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. Reported-and-tested-by: David Webb <djw@noc.ac.uk> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 1363074667a6b7d0507527742ccd7bbed5e3ceaa upstream.

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.

Reported-and-tested-by: David Webb <djw@noc.ac.uk>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
uas: Add US_FL_MAX_SECTORS_240 flag 2015-05-12T08:36:37+00:00 Hans de Goede hdegoede@redhat.com 2015-04-21T09:20:31+00:00 ad39619b358eee9868b05faf46e083352db3ab8d commit ee136af4a064c2f61e2025873584d2c7ec93f4ae upstream. 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. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit ee136af4a064c2f61e2025873584d2c7ec93f4ae upstream.

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.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Input: i8042 - reset keyboard to fix Elantech touchpad detection 2015-02-04T10:57:11+00:00 Srihari Vijayaraghavan linux.bug.reporting@gmail.com 2015-01-08T00:25:53+00:00 95eb9296727d8d2cea6a8d80b931734bcdb33fc4 commit 148e9a711e034e06310a8c36b64957934ebe30f2 upstream. On some laptops, keyboard needs to be reset in order to successfully detect touchpad (e.g., some Gigabyte laptop models with Elantech touchpads). Without resettin keyboard touchpad pretends to be completely dead. Based on the original patch by Mateusz Jończyk this version has been expanded to include DMI based detection & application of the fix automatically on the affected models of laptops. This has been confirmed to fix problem by three users already on three different models of laptops. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=81331 Signed-off-by: Srihari Vijayaraghavan <linux.bug.reporting@gmail.com> Acked-by: Mateusz Jończyk <mat.jonczyk@o2.pl> Tested-by: Srihari Vijayaraghavan <linux.bug.reporting@gmail.com> Tested by: Zakariya Dehlawi <zdehlawi@gmail.com> Tested-by: Guillaum Bouchard <guillaum.bouchard@gmail.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit 148e9a711e034e06310a8c36b64957934ebe30f2 upstream.

On some laptops, keyboard needs to be reset in order to successfully detect
touchpad (e.g., some Gigabyte laptop models with Elantech touchpads).
Without resettin keyboard touchpad pretends to be completely dead.

Based on the original patch by Mateusz Jończyk this version has been
expanded to include DMI based detection & application of the fix
automatically on the affected models of laptops. This has been confirmed to
fix problem by three users already on three different models of laptops.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=81331
Signed-off-by: Srihari Vijayaraghavan <linux.bug.reporting@gmail.com>
Acked-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Tested-by: Srihari Vijayaraghavan <linux.bug.reporting@gmail.com>
Tested by: Zakariya Dehlawi <zdehlawi@gmail.com>
Tested-by: Guillaum Bouchard <guillaum.bouchard@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
uas: Add no-report-opcodes quirk 2014-10-15T10:05:30+00:00 Hans de Goede hdegoede@redhat.com 2014-09-16T16:36:52+00:00 46816a619d8365ebbcfedbd83f74bcd2f004d81e commit 734016b00b50a3c6a0e1fc1b7b217e783f5123a1 upstream. Besides the ASM1051 (*) needing sdev->no_report_opcodes = 1, it turns out that the JMicron JMS567 also needs it to work properly with uas (usb-storage always sets it). Since some of the scsi devs were not to keen on the idea to outrightly set sdev->no_report_opcodes = 1 for all uas devices, so add a quirk for this, and set it for the JMS567. *) Which has become a non-issue since we've completely blacklisted uas on the ASM1051 for other reasons Reported-and-tested-by: Claudio Bizzarri <claudio.bizzarri@gmail.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 734016b00b50a3c6a0e1fc1b7b217e783f5123a1 upstream.

Besides the ASM1051 (*) needing sdev->no_report_opcodes = 1, it turns out that
the JMicron JMS567 also needs it to work properly with uas (usb-storage always
sets it). Since some of the scsi devs were not to keen on the idea to
outrightly set sdev->no_report_opcodes = 1 for all uas devices, so add a quirk
for this, and set it for the JMS567.

*) Which has become a non-issue since we've completely blacklisted uas on
the ASM1051 for other reasons

Reported-and-tested-by: Claudio Bizzarri <claudio.bizzarri@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uas: Add a quirk for rejecting ATA_12 and ATA_16 commands 2014-10-15T10:05:30+00:00 Hans de Goede hdegoede@redhat.com 2014-09-15T14:04:12+00:00 b1973083c479bb686fa44cb7aa0efa4312d6d2d8 commit 593078525c8b234a35a36ff551b8716464e86481 upstream. And set this quirk for the Seagate Expansion Desk (0bc2:2312), as that one seems to hang upon receiving an ATA_12 or ATA_16 command. https://bugzilla.kernel.org/show_bug.cgi?id=79511 https://bbs.archlinux.org/viewtopic.php?id=183190 While at it also add missing documentation for the u value for usb-storage quirks. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 593078525c8b234a35a36ff551b8716464e86481 upstream.

And set this quirk for the Seagate Expansion Desk (0bc2:2312), as that one
seems to hang upon receiving an ATA_12 or ATA_16 command.

https://bugzilla.kernel.org/show_bug.cgi?id=79511
https://bbs.archlinux.org/viewtopic.php?id=183190

While at it also add missing documentation for the u value for usb-storage
quirks.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
USB: document the 'u' flag for usb-storage quirks parameter 2014-10-05T20:40:58+00:00 Alan Stern stern@rowland.harvard.edu 2014-09-02T19:42:18+00:00 f6c523b67b8d38d5625aed6036f7eab284c36147 commit b6089f19fe0cec625b5963a851a07c3e412c27c8 upstream. Commit d24d481b7d36 (usb-storage: Modify and export adjust_quirks so that it can be used by uas) added the 'u' flag to the quirks module parameter for usb-storage, but neglected to update the documentation. This patch adds the documentation. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b6089f19fe0cec625b5963a851a07c3e412c27c8 upstream.

Commit d24d481b7d36 (usb-storage: Modify and export adjust_quirks so
that it can be used by uas) added the 'u' flag to the quirks module
parameter for usb-storage, but neglected to update the
documentation.  This patch adds the documentation.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-07-19T16:23:27+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-07-19T16:23:27+00:00 da5b99b4545e2bae9a08876e6e827589dbfdcd9a Pull RCU fixes from Thomas Gleixner: "Two RCU patches: - Address a serious performance regression on open/close caused by commit ac1bea85781e ("Make cond_resched() report RCU quiescent states") - Export RCU debug functions. Not a regression, but enablement to address a serious recursion bug in the sl*b allocators in 3.17" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcu: Reduce overhead of cond_resched() checks for RCU rcu: Export debug_init_rcu_head() and and debug_init_rcu_head() 
Pull RCU fixes from Thomas Gleixner:
 "Two RCU patches:
   - Address a serious performance regression on open/close caused by
     commit ac1bea85781e ("Make cond_resched() report RCU quiescent
     states")
   - Export RCU debug functions.  Not a regression, but enablement to
     address a serious recursion bug in the sl*b allocators in 3.17"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Reduce overhead of cond_resched() checks for RCU
  rcu: Export debug_init_rcu_head() and and debug_init_rcu_head()
Revert "ACPI / video: change acpi-video brightness_switch_enabled default to 0" 2014-07-14T18:10:27+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2014-07-14T17:35:45+00:00 2843768b701971ab10e62c77d5c75ad7c306f1bd This reverts commit 886129a8eebeb (ACPI / video: change acpi-video brightness_switch_enabled default to 0) as it is reported to cause problems to happen. Fixes: 886129a8eebeb (ACPI / video: change acpi-video brightness_switch_enabled default to 0) Link: http://marc.info/?l=linux-acpi&m=140534286826819&w=2 Reported by: Bjørn Mork <bjorn@mork.no> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
This reverts commit 886129a8eebeb (ACPI / video: change acpi-video
brightness_switch_enabled default to 0) as it is reported to cause
problems to happen.

Fixes: 886129a8eebeb (ACPI / video: change acpi-video brightness_switch_enabled default to 0)
Link: http://marc.info/?l=linux-acpi&m=140534286826819&w=2
Reported by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>