kernel/git/stable/linux.git/arch/arc, branch linux-4.11.y

mm: larger stack guard gap, between vmas

2017-06-24T05:06:22+00:00

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 Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds [wt: backport to 4.11: adjust context] Signed-off-by: Willy Tarreau Signed-off-by: Greg Kroah-Hartman

ARCv2: entry: save Accumulator register pair (r58:59) if present

2017-04-20T22:37:49+00:00

Accumulator is present in configs with FPU and/or DSP MPY (mpy > 6) Instead of doing this in pt_regs (and thus every kernel entry/exit), this could have been done in context switch (and for user task only) as currently kernel doesn't clobber these registers for its own accord. However we will soon start using 64-bit multiply instructions for kernel which can clobber these. Also gcc folks also plan to start using these as GPRs, hence better to always save/restore them Signed-off-by: Vineet Gupta

ARC: [plat-eznps] Fix build error

2017-04-14T16:56:06+00:00

Make ATOMIC_INIT available for all ARC platforms (including plat-eznps) Cc: # 4.9+ Signed-off-by: Noam Camus Signed-off-by: Vineet Gupta

Merge tag 'arc-4.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

2017-04-01T17:52:19+00:00

Pull ARC fixes from Vineet Gupta: "Accumulated fixes for ARC which I've been been sitting on for a while: - reading clk from driver vs device tree [Vlad] - fix support for UIO in VDK platform [Alexey] - SLC busy bit reading workaround - build warning with kprobes header reorg" * tag 'arc-4.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: ARC: fix build warnings with !CONFIG_KPROBES ARCv2: SLC: Make sure busy bit is set properly on SLC flushing ARC: vdk: Fix support of UIO ARCv2: make unimplemented vectors as no-ops rather than halt core ARC: get rate from clk driver instead of reading device tree ARC: [dts] add cpu nodes to ARCHS SMP device tree ARC: [dts] add input clocks for cpu nodes

ARC: fix build warnings with !CONFIG_KPROBES

2017-03-31T00:33:20+00:00

| CC lib/nmi_backtrace.o | In file included from ../include/linux/kprobes.h:43:0, | from ../lib/nmi_backtrace.c:17: | ../arch/arc/include/asm/kprobes.h:57:13: warning: 'trap_is_kprobe' defined but not used [-Wunused-function] | static void trap_is_kprobe(unsigned long address, struct pt_regs *regs) | ^~~~~~~~~~~~~~ The warning started with 7d134b2ce6 ("kprobes: move kprobe declarations to asm-generic/kprobes.h") which started including unconditionally into exposing a stub function for !CONFIG_KPROBES to rest of world. Fix that by making the stub a macro Signed-off-by: Vineet Gupta

ARCv2: SLC: Make sure busy bit is set properly on SLC flushing

2017-03-31T00:32:33+00:00

As reported in STAR 9001165532, an SLC control reg read (for checking busy state) right after SLC invalidate command may incorrectly return NOT busy causing software to NOT spin-wait while operation is underway. (and for some reason this only happens if L1 cache is also disabled - as required by IOC programming model) Suggested workaround is to do an additional Control Reg read, which ensures the 2nd read gets the right status. Cc: stable@vger.kernel.org #4.10 Signed-off-by: Alexey Brodkin [vgupta: reworte changelog a bit] Signed-off-by: Vineet Gupta

ARC: vdk: Fix support of UIO

2017-03-24T20:36:08+00:00

MotherBoard section has its "ranges" set to 0xE000_0000-0xF000_0000. But UIO node maps 4 different areas in different memory locations and all outside MB's ranges. That obviously breaks UIO mappings in runtime. Cc: Ruud Derwig Cc: stable@vger.kernel.org Signed-off-by: Alexey Brodkin Signed-off-by: Vineet Gupta

ARCv2: make unimplemented vectors as no-ops rather than halt core

2017-03-21T01:47:57+00:00

Signed-off-by: Vineet Gupta

arch, mm: convert all architectures to use 5level-fixup.h

2017-03-09T19:48:47+00:00

If an architecture uses 4level-fixup.h we don't need to do anything as it includes 5level-fixup.h. If an architecture uses pgtable-nop*d.h, define __ARCH_USE_5LEVEL_HACK before inclusion of the header. It makes asm-generic code to use 5level-fixup.h. If an architecture has 4-level paging or folds levels on its own, include 5level-fixup.h directly. Signed-off-by: Kirill A. Shutemov Acked-by: Michal Hocko Signed-off-by: Linus Torvalds

ARC: get rate from clk driver instead of reading device tree

2017-03-06T04:04:59+00:00

We were reading clock rate directly from device tree "clock-frequency" property of corresponding clock node in show_cpuinfo function. Such approach is correct only in case cpu is always clocked by "fixed-clock". If we use clock driver that allows rate to be changed this won't work as rate may change during the time or even "clock-frequency" property may not be presented at all. So this commit replaces reading device tree with getting rate from clock driver. This approach is much more flexible and will work for both fixed and mutable clocks. Signed-off-by: Vlad Zakharov Signed-off-by: Vineet Gupta