linux-stable.git/arch/s390/lib, branch linux-5.4.y

s390/uaccess: add missing earlyclobber annotations to __clear_user()

2023-04-05T09:16:46+00:00

commit 89aba4c26fae4e459f755a18912845c348ee48f3 upstream.

Add missing earlyclobber annotation to size, to, and tmp2 operands of the
__clear_user() inline assembly since they are modified or written to before
the last usage of all input operands. This can lead to incorrect register
allocation for the inline assembly.

Fixes: 6c2a9e6df604 ("[S390] Use alternative user-copy operations for new hardware.")
Reported-by: Mark Rutland 
Link: https://lore.kernel.org/all/20230321122514.1743889-3-mark.rutland@arm.com/
Cc: stable@vger.kernel.org
Reviewed-by: Gerald Schaefer 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390: fix strrchr() implementation

2021-10-20T09:40:12+00:00

commit 8e0ab8e26b72a80e991c66a8abc16e6c856abe3d upstream.

Fix two problems found in the strrchr() implementation for s390
architectures: evaluate empty strings (return the string address instead of
NULL, if '\0' is passed as second argument); evaluate the first character
of non-empty strings (the current implementation stops at the second).

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reported-by: Heiko Carstens  (incorrect behavior with empty strings)
Signed-off-by: Roberto Sassu 
Link: https://lore.kernel.org/r/20211005120836.60630-1-roberto.sassu@huawei.com
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390/mm: fix page table upgrade vs 2ndary address mode accesses

2020-04-29T14:33:25+00:00

commit 316ec154810960052d4586b634156c54d0778f74 upstream.

A page table upgrade in a kernel section that uses secondary address
mode will mess up the kernel instructions as follows:

Consider the following scenario: two threads are sharing memory.
On CPU1 thread 1 does e.g. strnlen_user().  That gets to
        old_fs = enable_sacf_uaccess();
        len = strnlen_user_srst(src, size);
and
                "   la    %2,0(%1)\n"
                "   la    %3,0(%0,%1)\n"
                "   slgr  %0,%0\n"
                "   sacf  256\n"
                "0: srst  %3,%2\n"
in strnlen_user_srst().  At that point we are in secondary space mode,
control register 1 points to kernel page table and instruction fetching
happens via c1, rather than usual c13.  Interrupts are not disabled, for
obvious reasons.

On CPU2 thread 2 does MAP_FIXED mmap(), forcing the upgrade of page table
from 3-level to e.g. 4-level one.  We'd allocated new top-level table,
set it up and now we hit this:
                notify = 1;
                spin_unlock_bh(&mm->page_table_lock);
        }
        if (notify)
                on_each_cpu(__crst_table_upgrade, mm, 0);
OK, we need to actually change over to use of new page table and we
need that to happen in all threads that are currently running.  Which
happens to include the thread 1.  IPI is delivered and we have
static void __crst_table_upgrade(void *arg)
{
        struct mm_struct *mm = arg;

        if (current->active_mm == mm)
                set_user_asce(mm);
        __tlb_flush_local();
}
run on CPU1.  That does
static inline void set_user_asce(struct mm_struct *mm)
{
        S390_lowcore.user_asce = mm->context.asce;
OK, user page table address updated...
        __ctl_load(S390_lowcore.user_asce, 1, 1);
... and control register 1 set to it.
        clear_cpu_flag(CIF_ASCE_PRIMARY);
}

IPI is run in home space mode, so it's fine - insns are fetched
using c13, which always points to kernel page table.  But as soon
as we return from the interrupt, previous PSW is restored, putting
CPU1 back into secondary space mode, at which point we no longer
get the kernel instructions from the kernel mapping.

The fix is to only fixup the control registers that are currently in use
for user processes during the page table update.  We must also disable
interrupts in enable_sacf_uaccess to synchronize the cr and
thread.mm_segment updates against the on_each-cpu.

Fixes: 0aaba41b58bc ("s390: remove all code using the access register mode")
Cc: stable@vger.kernel.org # 4.15+
Reported-by: Al Viro 
Reviewed-by: Gerald Schaefer 
References: CVE-2020-11884
Signed-off-by: Christian Borntraeger 
Signed-off-by: Greg Kroah-Hartman

Merge tag 's390-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2019-09-17T21:04:43+00:00

Pull s390 updates from Vasily Gorbik:

 - Add support for IBM z15 machines.

 - Add SHA3 and CCA AES cipher key support in zcrypt and pkey
   refactoring.

 - Move to arch_stack_walk infrastructure for the stack unwinder.

 - Various kasan fixes and improvements.

 - Various command line parsing fixes.

 - Improve decompressor phase debuggability.

 - Lift no bss usage restriction for the early code.

 - Use refcount_t for reference counters for couple of places in mm
   code.

 - Logging improvements and return code fix in vfio-ccw code.

 - Couple of zpci fixes and minor refactoring.

 - Remove some outdated documentation.

 - Fix secure boot detection.

 - Other various minor code clean ups.

* tag 's390-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (48 commits)
  s390: remove pointless drivers-y in drivers/s390/Makefile
  s390/cpum_sf: Fix line length and format string
  s390/pci: fix MSI message data
  s390: add support for IBM z15 machines
  s390/crypto: Support for SHA3 via CPACF (MSA6)
  s390/startup: add pgm check info printing
  s390/crypto: xts-aes-s390 fix extra run-time crypto self tests finding
  vfio-ccw: fix error return code in vfio_ccw_sch_init()
  s390: vfio-ap: fix warning reset not completed
  s390/base: remove unused s390_base_mcck_handler
  s390/sclp: Fix bit checked for has_sipl
  s390/zcrypt: fix wrong handling of cca cipher keygenflags
  s390/kasan: add kdump support
  s390/setup: avoid using strncmp with hardcoded length
  s390/sclp: avoid using strncmp with hardcoded length
  s390/module: avoid using strncmp with hardcoded length
  s390/pci: avoid using strncmp with hardcoded length
  s390/kaslr: reserve memory for kasan usage
  s390/mem_detect: provide single get_mem_detect_end
  s390/cmma: reuse kstrtobool for option value parsing
  ...

s390: clean .bss before running uncompressed kernel

2019-08-21T10:58:52+00:00

Clean uncompressed kernel .bss section in the startup code before
the uncompressed kernel is executed. At this point of time initrd and
certificates have been already rescued. Uncompressed kernel .bss size
is known from vmlinux_info. It is also taken into consideration during
uncompressed kernel positioning by kaslr (so it is safe to clean it).

With that uncompressed kernel is starting with .bss section zeroed and
no .bss section usage restrictions apply. Which makes chkbss checks for
uncompressed kernel objects obsolete and they can be removed.

early_nobss.c is also not needed anymore. Parts of it which are still
relevant are moved to early.c. Kasan initialization code is now called
directly from head64 (early.c is instrumented and should not be
executed before kasan shadow memory is set up).

Reviewed-by: Philipp Rudo 
Signed-off-by: Vasily Gorbik

s390/lib: add missing include

2019-07-29T16:05:02+00:00

Include  into arch/s390/lib/xor.c to expose xor_block_xc
declaration and avoid the following sparse warning:
arch/s390/lib/xor.c:128:27: warning: symbol 'xor_block_xc' was not declared. Should it be static?

Signed-off-by: Vasily Gorbik

s390: enforce CONFIG_SMP

2019-06-07T08:09:37+00:00

There never have been distributions that shiped with CONFIG_SMP=n for
s390. In addition the kernel currently doesn't even compile with
CONFIG_SMP=n for s390. Most likely it wouldn't even work, even if we
fix the compile error, since nobody tests it, since there is no use
case that I can think of.
Therefore simply enforce CONFIG_SMP and get rid of some more or
less unused code.

Reviewed-by: Christian Borntraeger 
Signed-off-by: Heiko Carstens

s390: add missing ENDPROC statements to assembler functions

2019-05-02T11:54:11+00:00

The assembler code in arch/s390 misses proper ENDPROC statements
to properly end functions in a few places. Add them.

Signed-off-by: Martin Schwidefsky

s390/kasan: improve string/memory functions checks

2019-01-18T08:34:18+00:00

Avoid using arch specific implementations of string/memory functions
with KASAN since gcc cannot instrument asm code memory accesses and
many bugs could be missed.

Acked-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/kasan: avoid user access code instrumentation

2018-10-09T09:21:21+00:00

Kasan instrumentation adds "store" check for variables marked as
modified by inline assembly. With user pointers containing addresses
from another address space this produces false positives.

static inline unsigned long clear_user_xc(void __user *to, ...)
{
	asm volatile(
	...
	: "+a" (to) ...

User space access functions are wrapped by manually instrumented
functions in kasan common code, which should be sufficient to catch
errors. So, we just disable uaccess.o instrumentation altogether.

Reviewed-by: Martin Schwidefsky 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky