linux-stable.git/arch, branch v4.4.65

x86, pmem: fix broken __copy_user_nocache cache-bypass assumptions

2017-04-27T07:09:34+00:00

commit 11e63f6d920d6f2dfd3cd421e939a4aec9a58dcd upstream.

Before we rework the "pmem api" to stop abusing __copy_user_nocache()
for memcpy_to_pmem() we need to fix cases where we may strand dirty data
in the cpu cache. The problem occurs when copy_from_iter_pmem() is used
for arbitrary data transfers from userspace. There is no guarantee that
these transfers, performed by dax_iomap_actor(), will have aligned
destinations or aligned transfer lengths. Backstop the usage
__copy_user_nocache() with explicit cache management in these unaligned
cases.

Yes, copy_from_iter_pmem() is now too big for an inline, but addressing
that is saved for a later patch that moves the entirety of the "pmem
api" into the pmem driver directly.

Fixes: 5de490daec8b ("pmem: add copy_from_iter_pmem() and clear_pmem()")
Cc: 
Cc: Jan Kara 
Cc: Jeff Moyer 
Cc: Ingo Molnar 
Cc: Christoph Hellwig 
Cc: "H. Peter Anvin" 
Cc: Al Viro 
Cc: Thomas Gleixner 
Cc: Matthew Wilcox 
Reviewed-by: Ross Zwisler 
Signed-off-by: Toshi Kani 
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd

2017-04-27T07:09:33+00:00

commit 8b3405e345b5a098101b0c31b264c812bba045d9 upstream.

In kvm_free_stage2_pgd() we don't hold the kvm->mmu_lock while calling
unmap_stage2_range() on the entire memory range for the guest. This could
cause problems with other callers (e.g, munmap on a memslot) trying to
unmap a range. And since we have to unmap the entire Guest memory range
holding a spinlock, make sure we yield the lock if necessary, after we
unmap each PUD range.

Fixes: commit d5d8184d35c9 ("KVM: ARM: Memory virtualization setup")
Cc: Paolo Bonzini 
Cc: Marc Zyngier 
Cc: Christoffer Dall 
Cc: Mark Rutland 
Signed-off-by: Suzuki K Poulose 
[ Avoid vCPU starvation and lockup detector warnings ]
Signed-off-by: Marc Zyngier 
Signed-off-by: Suzuki K Poulose 
Signed-off-by: Christoffer Dall 
Signed-off-by: Greg Kroah-Hartman

x86/mce/AMD: Give a name to MCA bank 3 when accessed with legacy MSRs

2017-04-27T07:09:33+00:00

commit 29f72ce3e4d18066ec75c79c857bee0618a3504b upstream.

MCA bank 3 is reserved on systems pre-Fam17h, so it didn't have a name.
However, MCA bank 3 is defined on Fam17h systems and can be accessed
using legacy MSRs. Without a name we get a stack trace on Fam17h systems
when trying to register sysfs files for bank 3 on kernels that don't
recognize Scalable MCA.

Call MCA bank 3 "decode_unit" since this is what it represents on
Fam17h. This will allow kernels without SMCA support to see this bank on
Fam17h+ and prevent the stack trace. This will not affect older systems
since this bank is reserved on them, i.e. it'll be ignored.

Tested on AMD Fam15h and Fam17h systems.

  WARNING: CPU: 26 PID: 1 at lib/kobject.c:210 kobject_add_internal
  kobject: (ffff88085bb256c0): attempted to be registered with empty name!
  ...
  Call Trace:
   kobject_add_internal
   kobject_add
   kobject_create_and_add
   threshold_create_device
   threshold_init_device

Signed-off-by: Yazen Ghannam 
Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/1490102285-3659-1-git-send-email-Yazen.Ghannam@amd.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

powerpc/kprobe: Fix oops when kprobed on 'stdu' instruction

2017-04-27T07:09:33+00:00

commit 9e1ba4f27f018742a1aa95d11e35106feba08ec1 upstream.

If we set a kprobe on a 'stdu' instruction on powerpc64, we see a kernel
OOPS:

  Bad kernel stack pointer cd93c840 at c000000000009868
  Oops: Bad kernel stack pointer, sig: 6 [#1]
  ...
  GPR00: c000001fcd93cb30 00000000cd93c840 c0000000015c5e00 00000000cd93c840
  ...
  NIP [c000000000009868] resume_kernel+0x2c/0x58
  LR [c000000000006208] program_check_common+0x108/0x180

On a 64-bit system when the user probes on a 'stdu' instruction, the kernel does
not emulate actual store in emulate_step() because it may corrupt the exception
frame. So the kernel does the actual store operation in exception return code
i.e. resume_kernel().

resume_kernel() loads the saved stack pointer from memory using lwz, which only
loads the low 32-bits of the address, causing the kernel crash.

Fix this by loading the 64-bit value instead.

Fixes: be96f63375a1 ("powerpc: Split out instruction analysis part of emulate_step()")
Signed-off-by: Ravi Bangoria 
Reviewed-by: Naveen N. Rao 
Reviewed-by: Ananth N Mavinakayanahalli 
[mpe: Change log massage, add stable tag]
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

s390/mm: fix CMMA vs KSM vs others

2017-04-27T07:09:32+00:00

commit a8f60d1fadf7b8b54449fcc9d6b15248917478ba upstream.

On heavy paging with KSM I see guest data corruption. Turns out that
KSM will add pages to its tree, where the mapping return true for
pte_unused (or might become as such later).  KSM will unmap such pages
and reinstantiate with different attributes (e.g. write protected or
special, e.g. in replace_page or write_protect_page)). This uncovered
a bug in our pagetable handling: We must remove the unused flag as
soon as an entry becomes present again.

Signed-of-by: Christian Borntraeger 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

MIPS: fix Select HAVE_IRQ_EXIT_ON_IRQ_STACK patch.

2017-04-21T07:30:08+00:00

Commit f017e58da4aba293e4a6ab62ca5d4801f79cc929 which was commit
3cc3434fd6307d06b53b98ce83e76bf9807689b9 upstream, was misapplied to the
4.4 stable kernel.

This patch fixes this and moves the chunk to the proper Kconfig area.

Reported-by: "Maciej W. Rozycki" 
Cc: Matt Redfearn 
Cc: Jason A. Donenfeld 
Cc: Thomas Gleixner 
Cc: Ralf Baechle 
Cc: Amit Pundir 
Signed-off-by: Greg Kroah-Hartman

mm: Tighten x86 /dev/mem with zeroing reads

2017-04-21T07:30:07+00:00

commit a4866aa812518ed1a37d8ea0c881dc946409de94 upstream.

Under CONFIG_STRICT_DEVMEM, reading System RAM through /dev/mem is
disallowed. However, on x86, the first 1MB was always allowed for BIOS
and similar things, regardless of it actually being System RAM. It was
possible for heap to end up getting allocated in low 1MB RAM, and then
read by things like x86info or dd, which would trip hardened usercopy:

usercopy: kernel memory exposure attempt detected from ffff880000090000 (dma-kmalloc-256) (4096 bytes)

This changes the x86 exception for the low 1MB by reading back zeros for
System RAM areas instead of blindly allowing them. More work is needed to
extend this to mmap, but currently mmap doesn't go through usercopy, so
hardened usercopy won't Oops the kernel.

Reported-by: Tommi Rantala 
Tested-by: Tommi Rantala 
Signed-off-by: Kees Cook 
Cc: Brad Spengler 
Signed-off-by: Greg Kroah-Hartman

powerpc: Disable HFSCR[TM] if TM is not supported

2017-04-21T07:30:06+00:00

commit 7ed23e1bae8bf7e37fd555066550a00b95a3a98b upstream.

On Power8 & Power9 the early CPU inititialisation in __init_HFSCR()
turns on HFSCR[TM] (Hypervisor Facility Status and Control Register
[Transactional Memory]), but that doesn't take into account that TM
might be disabled by CPU features, or disabled by the kernel being built
with CONFIG_PPC_TRANSACTIONAL_MEM=n.

So later in boot, when we have setup the CPU features, clear HSCR[TM] if
the TM CPU feature has been disabled. We use CPU_FTR_TM_COMP to account
for the CONFIG_PPC_TRANSACTIONAL_MEM=n case.

Without this a KVM guest might try use TM, even if told not to, and
cause an oops in the host kernel. Typically the oops is seen in
__kvmppc_vcore_entry() and may or may not be fatal to the host, but is
always bad news.

In practice all shipping CPU revisions do support TM, and all host
kernels we are aware of build with TM support enabled, so no one should
actually be able to hit this in the wild.

Fixes: 2a3563b023e5 ("powerpc: Setup in HFSCR for POWER8")
Cc: stable@vger.kernel.org # v3.10+
Signed-off-by: Benjamin Herrenschmidt 
Tested-by: Sam Bobroff 
[mpe: Rewrite change log with input from Sam, add Fixes/stable]
Signed-off-by: Michael Ellerman 
[sb: Backported to linux-4.4.y: adjusted context]
Signed-off-by: Sam Bobroff 
Signed-off-by: Greg Kroah-Hartman

kvm: fix page struct leak in handle_vmon

2017-04-21T07:30:06+00:00

commit 06ce521af9558814b8606c0476c54497cf83a653 upstream.

handle_vmon gets a reference on VMXON region page,
but does not release it. Release the reference.

Found by syzkaller; based on a patch by Dmitry.

Reported-by: Dmitry Vyukov 
Signed-off-by: Paolo Bonzini 
[bwh: Backported to 3.16: use skip_emulated_instruction()]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

Revert "MIPS: Lantiq: Fix cascaded IRQ setup"

2017-04-21T07:30:06+00:00

This reverts commit 6280ac931a23d3fa40cd26057576abcf90a4f22d which is
commit 6c356eda225e3ee134ed4176b9ae3a76f793f4dd upstream.

It shouldn't have been included in a stable release.

Reported-by: Amit Pundir 
Cc: Felix Fietkau 
Cc: John Crispin 
Cc: James Hogan 
Signed-off-by: Greg Kroah-Hartman