kernel-fxtec-pro1x/arch/s390
Heiko Carstens 02eb533e94 s390: fix stfle zero padding
commit 4f18d869ffd056c7858f3d617c71345cf19be008 upstream.

The stfle inline assembly returns the number of double words written
(condition code 0) or the double words it would have written
(condition code 3), if the memory array it got as parameter would have
been large enough.

The current stfle implementation assumes that the array is always
large enough and clears those parts of the array that have not been
written to with a subsequent memset call.

If however the array is not large enough memset will get a negative
length parameter, which means that memset clears memory until it gets
an exception and the kernel crashes.

To fix this simply limit the maximum length. Move also the inline
assembly to an extra function to avoid clobbering of register 0, which
might happen because of the added min_t invocation together with code
instrumentation.

The bug was introduced with commit 14375bc4eb ("[S390] cleanup
facility list handling") but was rather harmless, since it would only
write to a rather large array. It became a potential problem with
commit 3ab121ab18 ("[S390] kernel: Add z/VM LGR detection"). Since
then it writes to an array with only four double words, while some
machines already deliver three double words. As soon as machines have
a facility bit within the fifth double a crash on IPL would happen.

Fixes: 14375bc4eb ("[S390] cleanup facility list handling")
Cc: <stable@vger.kernel.org> # v2.6.37+
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-07-21 09:03:14 +02:00
..
appldata
boot s390/decompressor: add missing FORCE to build targets 2018-11-27 16:13:02 +01:00
configs
crypto s390/crypto: fix possible sleep during spinlock aquired 2019-06-09 09:17:16 +02:00
hypfs
include s390: fix stfle zero padding 2019-07-21 09:03:14 +02:00
kernel jump_label: move 'asm goto' support test to Kconfig 2019-06-04 08:02:34 +02:00
kvm KVM: s390: fix memory slot handling for KVM_SET_USER_MEMORY_REGION 2019-06-19 08:18:05 +02:00
lib
mm s390/mm: fix address space detection in exception handling 2019-06-11 12:20:53 +02:00
net Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2018-08-13 19:07:17 -07:00
numa s390/mm: Fix ERROR: "__node_distance" undefined! 2018-11-27 16:13:03 +01:00
oprofile
pci s390/pci: fix sleeping in atomic during hotplug 2019-01-09 17:38:41 +01:00
purgatory Kbuild updates for v4.19 2018-08-15 12:09:03 -07:00
scripts
tools Minor code cleanups for PPC. 2018-08-19 10:38:36 -07:00
defconfig crypto: speck - remove Speck 2018-11-13 11:08:46 -08:00
Kbuild
Kconfig Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2018-08-24 09:31:34 -07:00
Kconfig.debug
Makefile s390/boot: disable address-of-packed-member warning 2019-07-14 08:11:09 +02:00