4.9-stable patches

added patches:
	kasan-rework-kconfig-settings.patch

diff --git a/queue-4.9/kasan-rework-kconfig-settings.patch b/queue-4.9/kasan-rework-kconfig-settings.patch
new file mode 100644 (file)
index 0000000..accd0d3
--- /dev/null
+++ b/queue-4.9/kasan-rework-kconfig-settings.patch
@@ -0,0 +1,148 @@
+From e7c52b84fb18f08ce49b6067ae6285aca79084a8 Mon Sep 17 00:00:00 2001
+From: Arnd Bergmann <arnd@arndb.de>
+Date: Tue, 6 Feb 2018 15:41:41 -0800
+Subject: kasan: rework Kconfig settings
+
+From: Arnd Bergmann <arnd@arndb.de>
+
+commit e7c52b84fb18f08ce49b6067ae6285aca79084a8 upstream.
+
+We get a lot of very large stack frames using gcc-7.0.1 with the default
+-fsanitize-address-use-after-scope --param asan-stack=1 options, which can
+easily cause an overflow of the kernel stack, e.g.
+
+  drivers/gpu/drm/i915/gvt/handlers.c:2434:1: warning: the frame size of 46176 bytes is larger than 3072 bytes
+  drivers/net/wireless/ralink/rt2x00/rt2800lib.c:5650:1: warning: the frame size of 23632 bytes is larger than 3072 bytes
+  lib/atomic64_test.c:250:1: warning: the frame size of 11200 bytes is larger than 3072 bytes
+  drivers/gpu/drm/i915/gvt/handlers.c:2621:1: warning: the frame size of 9208 bytes is larger than 3072 bytes
+  drivers/media/dvb-frontends/stv090x.c:3431:1: warning: the frame size of 6816 bytes is larger than 3072 bytes
+  fs/fscache/stats.c:287:1: warning: the frame size of 6536 bytes is larger than 3072 bytes
+
+To reduce this risk, -fsanitize-address-use-after-scope is now split out
+into a separate CONFIG_KASAN_EXTRA Kconfig option, leading to stack
+frames that are smaller than 2 kilobytes most of the time on x86_64.  An
+earlier version of this patch also prevented combining KASAN_EXTRA with
+KASAN_INLINE, but that is no longer necessary with gcc-7.0.1.
+
+All patches to get the frame size below 2048 bytes with CONFIG_KASAN=y
+and CONFIG_KASAN_EXTRA=n have been merged by maintainers now, so we can
+bring back that default now.  KASAN_EXTRA=y still causes lots of
+warnings but now defaults to !COMPILE_TEST to disable it in
+allmodconfig, and it remains disabled in all other defconfigs since it
+is a new option.  I arbitrarily raise the warning limit for KASAN_EXTRA
+to 3072 to reduce the noise, but an allmodconfig kernel still has around
+50 warnings on gcc-7.
+
+I experimented a bit more with smaller stack frames and have another
+follow-up series that reduces the warning limit for 64-bit architectures
+to 1280 bytes (without CONFIG_KASAN).
+
+With earlier versions of this patch series, I also had patches to address
+the warnings we get with KASAN and/or KASAN_EXTRA, using a
+"noinline_if_stackbloat" annotation.
+
+That annotation now got replaced with a gcc-8 bugfix (see
+https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715) and a workaround for
+older compilers, which means that KASAN_EXTRA is now just as bad as
+before and will lead to an instant stack overflow in a few extreme
+cases.
+
+This reverts parts of commit 3f181b4d8652 ("lib/Kconfig.debug: disable
+-Wframe-larger-than warnings with KASAN=y").  Two patches in linux-next
+should be merged first to avoid introducing warnings in an allmodconfig
+build:
+  3cd890dbe2a4 ("media: dvb-frontends: fix i2c access helpers for KASAN")
+  16c3ada89cff ("media: r820t: fix r820t_write_reg for KASAN")
+
+Do we really need to backport this?
+
+I think we do: without this patch, enabling KASAN will lead to
+unavoidable kernel stack overflow in certain device drivers when built
+with gcc-7 or higher on linux-4.10+ or any version that contains a
+backport of commit c5caf21ab0cf8.  Most people are probably still on
+older compilers, but it will get worse over time as they upgrade their
+distros.
+
+The warnings we get on kernels older than this should all be for code
+that uses dangerously large stack frames, though most of them do not
+cause an actual stack overflow by themselves.The asan-stack option was
+added in linux-4.0, and commit 3f181b4d8652 ("lib/Kconfig.debug:
+disable -Wframe-larger-than warnings with KASAN=y") effectively turned
+off the warning for allmodconfig kernels, so I would like to see this
+fix backported to any kernels later than 4.0.
+
+I have done dozens of fixes for individual functions with stack frames
+larger than 2048 bytes with asan-stack, and I plan to make sure that
+all those fixes make it into the stable kernels as well (most are
+already there).
+
+Part of the complication here is that asan-stack (from 4.0) was
+originally assumed to always require much larger stacks, but that
+turned out to be a combination of multiple gcc bugs that we have now
+worked around and fixed, but sanitize-address-use-after-scope (from
+v4.10) has a much higher inherent stack usage and also suffers from at
+least three other problems that we have analyzed but not yet fixed
+upstream, each of them makes the stack usage more severe than it should
+be.
+
+Link: http://lkml.kernel.org/r/20171221134744.2295529-1-arnd@arndb.de
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
+Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
+Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
+Cc: Alexander Potapenko <glider@google.com>
+Cc: Dmitry Vyukov <dvyukov@google.com>
+Cc: Andrey Konovalov <andreyknvl@google.com>
+Cc: <stable@vger.kernel.org>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ lib/Kconfig.debug      |    1 +
+ lib/Kconfig.kasan      |   11 +++++++++++
+ scripts/Makefile.kasan |    2 ++
+ 3 files changed, 14 insertions(+)
+
+--- a/lib/Kconfig.debug
++++ b/lib/Kconfig.debug
+@@ -197,6 +197,7 @@ config ENABLE_MUST_CHECK
+ config FRAME_WARN
+       int "Warn for stack frames larger than (needs gcc 4.4)"
+       range 0 8192
++      default 3072 if KASAN_EXTRA
+       default 2048 if GCC_PLUGIN_LATENT_ENTROPY
+       default 1024 if !64BIT
+       default 2048 if 64BIT
+--- a/lib/Kconfig.kasan
++++ b/lib/Kconfig.kasan
+@@ -20,6 +20,17 @@ config KASAN
+         Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
+         (the resulting kernel does not boot).
+ 
++config KASAN_EXTRA
++      bool "KAsan: extra checks"
++      depends on KASAN && DEBUG_KERNEL && !COMPILE_TEST
++      help
++        This enables further checks in the kernel address sanitizer, for now
++        it only includes the address-use-after-scope check that can lead
++        to excessive kernel stack usage, frame size warnings and longer
++        compile time.
++        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
++
++
+ choice
+       prompt "Instrumentation type"
+       depends on KASAN
+--- a/scripts/Makefile.kasan
++++ b/scripts/Makefile.kasan
+@@ -29,7 +29,9 @@ else
+     endif
+ endif
+ 
++ifdef CONFIG_KASAN_EXTRA
+ CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope)
++endif
+ 
+ CFLAGS_KASAN_NOSANITIZE := -fno-builtin
+ 

diff --git a/queue-4.9/series b/queue-4.9/series
index 8713de6202a952827cea810ccee75e54abf923a9..90a94e00e7de1b7a76b847acf8c6f52989ca5163 100644 (file)
--- a/queue-4.9/series
+++ b/queue-4.9/series
@@ -7,6 +7,7 @@ bnxt_en-improve-multicast-address-setup-logic.patch
 net-phy-marvell-fix-buffer-overrun-with-stats-counters.patch
 x86-suspend-fix-false-positive-kasan-warning-on-suspend-resume.patch
 kasan-turn-on-fsanitize-address-use-after-scope.patch
+kasan-rework-kconfig-settings.patch
 mm-kasan-switch-to-using-__pa_symbol-and-lm_alias.patch
 x86-unwind-disable-kasan-checks-for-non-current-tasks.patch
 arm64-kasan-avoid-bad-virt_to_pfn.patch