linux-stable.git/arch, branch linux-2.6.32.y

sparc64: fix incorrect sign extension in sys_sparc64_personality

2016-03-12T13:25:40+00:00

commit 525fd5a94e1be0776fa652df5c687697db508c91 upstream.

The value returned by sys_personality has type "long int".
It is saved to a variable of type "int", which is not a problem
yet because the type of task_struct->pesonality is "unsigned int".
The problem is the sign extension from "int" to "long int"
that happens on return from sys_sparc64_personality.

For example, a userspace call personality((unsigned) -EINVAL) will
result to any subsequent personality call, including absolutely
harmless read-only personality(0xffffffff) call, failing with
errno set to EINVAL.

Signed-off-by: Dmitry V. Levin 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

x86/mm/pat: Avoid truncation when converting cpa->numpages to address

2016-03-12T13:25:40+00:00

commit 742563777e8da62197d6cb4b99f4027f59454735 upstream.

There are a couple of nasty truncation bugs lurking in the pageattr
code that can be triggered when mapping EFI regions, e.g. when we pass
a cpa->pgd pointer. Because cpa->numpages is a 32-bit value, shifting
left by PAGE_SHIFT will truncate the resultant address to 32-bits.

Viorel-CÄtÄlin managed to trigger this bug on his Dell machine that
provides a ~5GB EFI region which requires 1236992 pages to be mapped.
When calling populate_pud() the end of the region gets calculated
incorrectly in the following buggy expression,

  end = start + (cpa->numpages << PAGE_SHIFT);

And only 188416 pages are mapped. Next, populate_pud() gets invoked
for a second time because of the loop in __change_page_attr_set_clr(),
only this time no pages get mapped because shifting the remaining
number of pages (1048576) by PAGE_SHIFT is zero. At which point the
loop in __change_page_attr_set_clr() spins forever because we fail to
map progress.

Hitting this bug depends very much on the virtual address we pick to
map the large region at and how many pages we map on the initial run
through the loop. This explains why this issue was only recently hit
with the introduction of commit

  a5caa209ba9c ("x86/efi: Fix boot crash by mapping EFI memmap
   entries bottom-up at runtime, instead of top-down")

It's interesting to note that safe uses of cpa->numpages do exist in
the pageattr code. If instead of shifting ->numpages we multiply by
PAGE_SIZE, no truncation occurs because PAGE_SIZE is a UL value, and
so the result is unsigned long.

To avoid surprises when users try to convert very large cpa->numpages
values to addresses, change the data type from 'int' to 'unsigned
long', thereby making it suitable for shifting by PAGE_SHIFT without
any type casting.

The alternative would be to make liberal use of casting, but that is
far more likely to cause problems in the future when someone adds more
code and fails to cast properly; this bug was difficult enough to
track down in the first place.

Reported-and-tested-by: Viorel-CÄtÄlin RÄpiÈeanu 
Acked-by: Borislav Petkov 
Cc: Sai Praneeth Prakhya 
Signed-off-by: Matt Fleming 
Link: https://bugzilla.kernel.org/show_bug.cgi?id=110131
Link: http://lkml.kernel.org/r/1454067370-10374-1-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

x86/mm: Improve switch_mm() barrier comments

2016-03-12T13:25:40+00:00

commit 4eaffdd5a5fe6ff9f95e1ab4de1ac904d5e0fa8b upstream.

My previous comments were still a bit confusing and there was a
typo. Fix it up.

Reported-by: Peter Zijlstra 
Signed-off-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Rik van Riel 
Cc: Thomas Gleixner 
Fixes: 71b3c126e611 ("x86/mm: Add barriers and document switch_mm()-vs-flush synchronization")
Link: http://lkml.kernel.org/r/0a0b43cdcdd241c5faaaecfbcc91a155ddedc9a1.1452631609.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

x86/mm: Add barriers and document switch_mm()-vs-flush synchronization

2016-03-12T13:25:40+00:00

commit 71b3c126e61177eb693423f2e18a1914205b165e upstream.

When switch_mm() activates a new PGD, it also sets a bit that
tells other CPUs that the PGD is in use so that TLB flush IPIs
will be sent.  In order for that to work correctly, the bit
needs to be visible prior to loading the PGD and therefore
starting to fill the local TLB.

Document all the barriers that make this work correctly and add
a couple that were missing.

Signed-off-by: Andy Lutomirski 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Thomas Gleixner 
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar 
[bwh: Backported to 2.6.32:
 - There's no flush_tlb_mm_range(), only flush_tlb_mm() which does not use
   INVLPG
 - Adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

kvm: x86: only channel 0 of the i8254 is linked to the HPET

2016-01-29T21:12:59+00:00

commit e5e57e7a03b1cdcb98e4aed135def2a08cbf3257 upstream.

While setting the KVM PIT counters in 'kvm_pit_load_count', if
'hpet_legacy_start' is set, the function disables the timer on
channel[0], instead of the respective index 'channel'. This is
because channels 1-3 are not linked to the HPET.  Fix the caller
to only activate the special HPET processing for channel 0.

Reported-by: P J P 
Fixes: 0185604c2d82c560dab2f2933a18f797e74ab5a8
Signed-off-by: Paolo Bonzini 
Signed-off-by: Ben Hutchings 
(cherry picked from commit ef90cf3d0b59e3b1dcfe94d1a241107667e6e96a)
Signed-off-by: Willy Tarreau

KVM: x86: Reload pit counters for all channels when restoring state

2016-01-29T21:12:59+00:00

commit 0185604c2d82c560dab2f2933a18f797e74ab5a8 upstream.

Currently if userspace restores the pit counters with a count of 0
on channels 1 or 2 and the guest attempts to read the count on those
channels, then KVM will perform a mod of 0 and crash.  This will ensure
that 0 values are converted to 65536 as per the spec.

This is CVE-2015-7513.

Signed-off-by: Andy Honig 
Signed-off-by: Paolo Bonzini 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings 
(cherry picked from commit 08b8d1a6ccdefd3d517d04c472b7f42f51b3059b)
Signed-off-by: Willy Tarreau

parisc: Fix syscall restarts

2016-01-29T21:12:56+00:00

commit 71a71fb5374a23be36a91981b5614590b9e722c3 upstream.

On parisc syscalls which are interrupted by signals sometimes failed to
restart and instead returned -ENOSYS which in the worst case lead to
userspace crashes.
A similiar problem existed on MIPS and was fixed by commit e967ef02
("MIPS: Fix restart of indirect syscalls").

On parisc the current syscall restart code assumes that all syscall
callers load the syscall number in the delay slot of the ble
instruction. That's how it is e.g. done in the unistd.h header file:
	ble 0x100(%sr2, %r0)
	ldi #syscall_nr, %r20
Because of that assumption the current code never restored %r20 before
returning to userspace.

This assumption is at least not true for code which uses the glibc
syscall() function, which instead uses this syntax:
	ble 0x100(%sr2, %r0)
	copy regX, %r20
where regX depend on how the compiler optimizes the code and register
usage.

This patch fixes this problem by adding code to analyze how the syscall
number is loaded in the delay branch and - if needed - copy the syscall
number to regX prior returning to userspace for the syscall restart.

Signed-off-by: Helge Deller 
Cc: Mathieu Desnoyers 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings 
(cherry picked from commit 9f2dcffefc599c424ad1dd402e3a96da60639308)
Signed-off-by: Willy Tarreau

MIPS: Fix restart of indirect syscalls

2016-01-29T21:12:56+00:00

commit e967ef022e00bb7c2e5b1a42007abfdd52055050 upstream.

When 32-bit MIPS userspace invokes a syscall indirectly via syscall(number,
arg1, ..., arg7), the kernel looks up the actual syscall based on the given
number, shifts the other arguments to the left, and jumps to the syscall.

If the syscall is interrupted by a signal and indicates it needs to be
restarted by the kernel (by returning ERESTARTNOINTR for example), the
syscall must be called directly, since the number is no longer the first
argument, and the other arguments are now staged for a direct call.

Before shifting the arguments, store the syscall number in pt_regs->regs[2].
This gets copied temporarily into pt_regs->regs[0] after the syscall returns.
If the syscall needs to be restarted, handle_signal()/do_signal() copies the
number back to pt_regs->reg[2], which ends up in $v0 once control returns to
userspace.

Signed-off-by: Ed Swierk 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8929/
Signed-off-by: Ralf Baechle 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings 
(cherry picked from commit 08f865bba9c705aef95268a33393698e5385587e)
Signed-off-by: Willy Tarreau

s390/dis: Fix handling of format specifiers

2016-01-29T21:12:54+00:00

commit 272fa59ccb4fc802af28b1d699c2463db6a71bf7 upstream.

The print_insn() function returns strings like "lghi %r1,0". To escape the
'%' character in sprintf() a second '%' is used. For example "lghi %%r1,0"
is converted into "lghi %r1,0".

After print_insn() the output string is passed to printk(). Because format
specifiers like "%r" or "%f" are ignored by printk() this works by chance
most of the time. But for instructions with control registers like
"lctl %c6,%c6,780" this fails because printk() interprets "%c" as
character format specifier.

Fix this problem and escape the '%' characters twice.

For example "lctl %%%%c6,%%%%c6,780" is then converted by sprintf()
into "lctl %%c6,%%c6,780" and by printk() into "lctl %c6,%c6,780".

Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky 
[bwh: Backported to 3.2: drop the OPERAND_VR case]
Signed-off-by: Ben Hutchings 
(cherry picked from commit 45f32e359d36dd045e4af0d1bea8bbbafd81eeb7)
Signed-off-by: Willy Tarreau

x86/process: Add proper bound checks in 64bit get_wchan()

2015-12-05T23:49:14+00:00

commit eddd3826a1a0190e5235703d1e666affa4d13b96 upstream.

Dmitry Vyukov reported the following using trinity and the memory
error detector AddressSanitizer
(https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel).

[ 124.575597] ERROR: AddressSanitizer: heap-buffer-overflow on
address ffff88002e280000
[ 124.576801] ffff88002e280000 is located 131938492886538 bytes to
the left of 28857600-byte region [ffffffff81282e0a, ffffffff82e0830a)
[ 124.578633] Accessed by thread T10915:
[ 124.579295] inlined in describe_heap_address
./arch/x86/mm/asan/report.c:164
[ 124.579295] #0 ffffffff810dd277 in asan_report_error
./arch/x86/mm/asan/report.c:278
[ 124.580137] #1 ffffffff810dc6a0 in asan_check_region
./arch/x86/mm/asan/asan.c:37
[ 124.581050] #2 ffffffff810dd423 in __tsan_read8 ??:0
[ 124.581893] #3 ffffffff8107c093 in get_wchan
./arch/x86/kernel/process_64.c:444

The address checks in the 64bit implementation of get_wchan() are
wrong in several ways:

 - The lower bound of the stack is not the start of the stack
   page. It's the start of the stack page plus sizeof (struct
   thread_info)

 - The upper bound must be:

       top_of_stack - TOP_OF_KERNEL_STACK_PADDING - 2 * sizeof(unsigned long).

   The 2 * sizeof(unsigned long) is required because the stack pointer
   points at the frame pointer. The layout on the stack is: ... IP FP
   ... IP FP. So we need to make sure that both IP and FP are in the
   bounds.

Fix the bound checks and get rid of the mix of numeric constants, u64
and unsigned long. Making all unsigned long allows us to use the same
function for 32bit as well.

Use READ_ONCE() when accessing the stack. This does not prevent a
concurrent wakeup of the task and the stack changing, but at least it
avoids TOCTOU.

Also check task state at the end of the loop. Again that does not
prevent concurrent changes, but it avoids walking for nothing.

Add proper comments while at it.

Reported-by: Dmitry Vyukov 
Reported-by: Sasha Levin 
Based-on-patch-from: Wolfram Gloger 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Borislav Petkov 
Reviewed-by: Dmitry Vyukov 
Cc: Andrey Ryabinin 
Cc: Andy Lutomirski 
Cc: Andrey Konovalov 
Cc: Kostya Serebryany 
Cc: Alexander Potapenko 
Cc: kasan-dev 
Cc: Denys Vlasenko 
Cc: Andi Kleen 
Cc: Wolfram Gloger 
Link: http://lkml.kernel.org/r/20150930083302.694788319@linutronix.de
Signed-off-by: Thomas Gleixner 
[bwh: Backported to 3.2:
 - s/READ_ONCE/ACCESS_ONCE/
 - Remove use of TOP_OF_KERNEL_STACK_PADDING, not defined here and would
   be defined as 0]
Signed-off-by: Ben Hutchings 
(cherry picked from commit 5311d93d0d33ae878d5fbb35ea5693b9c813ba04)

Signed-off-by: Willy Tarreau