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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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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>
Pull ARM SoC fixes from Olof Johansson:
"Stream of fixes has slowed down, only a few this week:
- Some DT fixes for Allwinner platforms, and addition of a clock to
the R_CCU clock controller that had been missed.
- A couple of small DT fixes for am335x-sl50"
* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
arm64: allwinner: a64: Add PLL_PERIPH0 clock to the R_CCU
ARM: sunxi: h3-h5: Add PLL_PERIPH0 clock to the R_CCU
ARM: dts: am335x-sl50: Fix cannot claim requested pins for spi0
ARM: dts: am335x-sl50: Fix card detect pin for mmc1
arm64: allwinner: h5: Remove syslink to shared DTSI
ARM: sunxi: h3/h5: fix the compatible of R_CCU
Pull virtio bugfix from Michael Tsirkin:
"It turns out balloon does not handle IOMMUs correctly. We should fix
that at some point, for now let's just disable this configuration"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
virtio_balloon: disable VIOMMU support
Allwinner fixes for 4.12
A few fixes around the PRCM support that got in 4.12 with a wrong
compatible, and a missing clock in the binding.
* tag 'sunxi-fixes-for-4.12' of https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux:
arm64: allwinner: a64: Add PLL_PERIPH0 clock to the R_CCU
ARM: sunxi: h3-h5: Add PLL_PERIPH0 clock to the R_CCU
arm64: allwinner: h5: Remove syslink to shared DTSI
ARM: sunxi: h3/h5: fix the compatible of R_CCU
Signed-off-by: Olof Johansson <olof@lixom.net>
Pull i2c fixes from Wolfram Sang:
"Two driver bugfixes"
* 'i2c/for-current-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: ismt: fix wrong device address when unmap the data buffer
i2c: rcar: use correct length when unmapping DMA
virtio balloon bypasses the DMA API entirely so does not support the
VIOMMU right now. It's not clear we need that support, for now let's
just make sure we don't pretend to support it.
Cc: stable@vger.kernel.org
Cc: Wei Wang <wei.w.wang@intel.com>
Fixes: 1a937693993f ("virtio: new feature to detect IOMMU device quirk")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Two fixes for am335x-sl50 to fix a boot time error
for claiming SPI pins, and to fix a SDIO card detect
pin for production version of the device.
* tag 'omap-for-v4.12/fixes-sl50' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
ARM: dts: am335x-sl50: Fix cannot claim requested pins for spi0
ARM: dts: am335x-sl50: Fix card detect pin for mmc1
Signed-off-by: Olof Johansson <olof@lixom.net>
The AR100 clock within the R_CCU (PRCM) has the PLL_PERIPH0 as one of
its parents.
This adds the reference in the device tree describing this relationship.
This patch uses a raw number for the clock index to ease merging by
avoiding cross tree dependencies.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Pull MIPS fixes from Ralf Baechle:
- Three highmem fixes:
+ Fixed mapping initialization
+ Adjust the pkmap location
+ Ensure we use at most one page for PTEs
- Fix makefile dependencies for .its targets to depend on vmlinux
- Fix reversed condition in BNEZC and JIALC software branch emulation
- Only flush initialized flush_insn_slot to avoid NULL pointer
dereference
- perf: Remove incorrect odd/even counter handling for I6400
- ftrace: Fix init functions tracing
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
MIPS: .its targets depend on vmlinux
MIPS: Fix bnezc/jialc return address calculation
MIPS: kprobes: flush_insn_slot should flush only if probe initialised
MIPS: ftrace: fix init functions tracing
MIPS: mm: adjust PKMAP location
MIPS: highmem: ensure that we don't use more than one page for PTEs
MIPS: mm: fixed mappings: correct initialisation
MIPS: perf: Remove incorrect odd/even counter handling for I6400
Fix the following kernel bug:
kernel BUG at drivers/iommu/intel-iommu.c:3260!
invalid opcode: 0000 [#5] PREEMPT SMP
Hardware name: Intel Corp. Harcuvar/Server, BIOS HAVLCRB0.X64.0013.D39.1608311820 08/31/2016
task: ffff880175389950 ti: ffff880176bec000 task.ti: ffff880176bec000
RIP: 0010:[<ffffffff8150a83b>] [<ffffffff8150a83b>] intel_unmap+0x25b/0x260
RSP: 0018:ffff880176bef5e8 EFLAGS: 00010296
RAX: 0000000000000024 RBX: ffff8800773c7c88 RCX: 000000000000ce04
RDX: 0000000080000000 RSI: 0000000000000000 RDI: 0000000000000009
RBP: ffff880176bef638 R08: 0000000000000010 R09: 0000000000000004
R10: ffff880175389c78 R11: 0000000000000a4f R12: ffff8800773c7868
R13: 00000000ffffac88 R14: ffff8800773c7818 R15: 0000000000000001
FS: 00007fef21258700(0000) GS:ffff88017b5c0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000066d6d8 CR3: 000000007118c000 CR4: 00000000003406e0
Stack:
00000000ffffac88 ffffffff8199867f ffff880176bef5f8 ffff880100000030
ffff880176bef668 ffff8800773c7c88 ffff880178288098 ffff8800772c0010
ffff8800773c7818 0000000000000001 ffff880176bef648 ffffffff8150a86e
Call Trace:
[<ffffffff8199867f>] ? printk+0x46/0x48
[<ffffffff8150a86e>] intel_unmap_page+0xe/0x10
[<ffffffffa039d99b>] ismt_access+0x27b/0x8fa [i2c_ismt]
[<ffffffff81554420>] ? __pm_runtime_suspend+0xa0/0xa0
[<ffffffff815544a0>] ? pm_suspend_timer_fn+0x80/0x80
[<ffffffff81554420>] ? __pm_runtime_suspend+0xa0/0xa0
[<ffffffff815544a0>] ? pm_suspend_timer_fn+0x80/0x80
[<ffffffff8143dfd0>] ? pci_bus_read_dev_vendor_id+0xf0/0xf0
[<ffffffff8172b36c>] i2c_smbus_xfer+0xec/0x4b0
[<ffffffff810aa4d5>] ? vprintk_emit+0x345/0x530
[<ffffffffa038936b>] i2cdev_ioctl_smbus+0x12b/0x240 [i2c_dev]
[<ffffffff810aa829>] ? vprintk_default+0x29/0x40
[<ffffffffa0389b33>] i2cdev_ioctl+0x63/0x1ec [i2c_dev]
[<ffffffff811b04c8>] do_vfs_ioctl+0x328/0x5d0
[<ffffffff8119d8ec>] ? vfs_write+0x11c/0x190
[<ffffffff8109d449>] ? rt_up_read+0x19/0x20
[<ffffffff811b07f1>] SyS_ioctl+0x81/0xa0
[<ffffffff819a351b>] system_call_fastpath+0x16/0x6e
This happen When run "i2cdetect -y 0" detect SMBus iSMT adapter.
After finished I2C block read/write, when unmap the data buffer,
a wrong device address was pass to dma_unmap_single().
To fix this, give dma_unmap_single() the "dev" parameter, just like
what dma_map_single() does, then unmap can find the right devices.
Fixes: 13f35ac14cd0 ("i2c: Adding support for Intel iSMT SMBus 2.0 host controller")
Signed-off-by: Liwei Song <liwei.song@windriver.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
As agreed with Ryan, change the maintainership.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Acked-by: Ryan Mallon <rmallon@gmail.com>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
We don't need to bitbang these pins anymore, instead we muxed these
pins as SPI, after this change, done in commit 6c69f726, we introduced
the following error:
pinctrl-single 44e10800.pinmux: pin PIN85 already requested \
by 44e10800.pinmux; cannot claim for 48030000.spi
pinctrl-single 44e10800.pinmux: pin-85 (48030000.spi) status -22
Fixes: 6c69f726 ("ARM: dts: am335x-sl50: Enable SPI0 interface and Flash Memory")
Cc: <stable@vger.kernel.org> # 4.11
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
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