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Dave Hansen 2056e2989b x86/sgx: Fix NULL pointer dereference on non-SGX systems
== Problem ==

Nathan Chancellor reported an oops when aceessing the
'sgx_total_bytes' sysfs file:

	https://lore.kernel.org/all/YbzhBrimHGGpddDM@archlinux-ax161/

The sysfs output code accesses the sgx_numa_nodes[] array
unconditionally.  However, this array is allocated during SGX
initialization, which only occurs on systems where SGX is
supported.

If the sysfs file is accessed on systems without SGX support,
sgx_numa_nodes[] is NULL and an oops occurs.

== Solution ==

To fix this, hide the entire nodeX/x86/ attribute group on
systems without SGX support using the ->is_visible attribute
group callback.

Unfortunately, SGX is initialized via a device_initcall() which
occurs _after_ the ->is_visible() callback.  Instead of moving
SGX initialization earlier, call sysfs_update_group() during
SGX initialization to update the group visiblility.

This update requires moving the SGX sysfs code earlier in
sgx/main.c.  There are no code changes other than the addition of
arch_update_sysfs_visibility() and a minor whitespace fixup to
arch_node_attr_is_visible() which checkpatch caught.

CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-sgx@vger.kernel.org
Cc: x86@kernel.org
Fixes: 50468e4313 ("x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/20220104171527.5E8416A8@davehans-spike.ostc.intel.com
2022-01-07 08:47:23 -08:00
arch x86/sgx: Fix NULL pointer dereference on non-SGX systems 2022-01-07 08:47:23 -08:00
block blk-mq: fix filesystem I/O request allocation 2021-11-12 09:31:13 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node 2021-12-09 07:02:22 -08:00
drivers x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node 2021-12-09 07:02:22 -08:00
fs Minor tweaks for 5.16: 2021-11-14 12:18:22 -08:00
include x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node 2021-12-09 07:02:22 -08:00
init kconfig: Add support for -Wimplicit-fallthrough 2021-11-14 13:27:30 -08:00
ipc ipc/ipc_sysctl.c: remove fallback for !CONFIG_PROC_SYSCTL 2021-11-09 10:02:53 -08:00
kernel A single fix for POSIX CPU timers to address a problem where POSIX CPU 2021-11-14 10:43:38 -08:00
lib Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm x86/sgx: Hook arch_memory_failure() into mainline code 2021-11-15 11:13:16 -08:00
net One notable change here is that async creates and unlinks introduced 2021-11-13 11:31:07 -08:00
samples Add gitignore file for samples/fanotify/ subdirectory 2021-11-07 11:19:24 -08:00
scripts coccinelle patches for 5.16-rc1 2021-11-13 10:45:17 -08:00
security net,lsm,selinux: revert the security_sctp_assoc_established() hook 2021-11-12 12:07:02 -05:00
sound sound fixes for 5.16-rc1 2021-11-12 12:17:30 -08:00
tools selftests/sgx: Fix corrupted cpuid macro invocation 2021-12-17 08:52:33 -08:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt KVM: generalize "bugged" VM to "dead" VM 2021-11-11 10:35:26 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS - Add the model number of a new, Raptor Lake CPU, to intel-family.h 2021-11-14 09:29:03 -08:00
Makefile Linux 5.16-rc1 2021-11-14 13:56:52 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.