openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/fs/hfsplus/Kconfig b/fs/hfsplus/Kconfig
new file mode 100644
index 000000000..ca8401cb6
--- /dev/null
+++ b/fs/hfsplus/Kconfig
@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config HFSPLUS_FS
+	tristate "Apple Extended HFS file system support"
+	depends on BLOCK
+	select BUFFER_HEAD
+	select NLS
+	select NLS_UTF8
+	select LEGACY_DIRECT_IO
+	help
+	  If you say Y here, you will be able to mount extended format
+	  Macintosh-formatted hard drive partitions with full read-write access.
+
+	  This file system is often called HFS+ and was introduced with
+	  MacOS 8. It includes all Mac specific filesystem data such as
+	  data forks and creator codes, but it also has several UNIX
+	  style features such as file ownership and permissions.
+
+config HFSPLUS_KUNIT_TEST
+	tristate "KUnit tests for HFS+ filesystem" if !KUNIT_ALL_TESTS
+	depends on HFSPLUS_FS && KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds KUnit tests for the HFS+ filesystem.
+
+	  KUnit tests run during boot and output the results to the debug
+	  log in TAP format (https://testanything.org/). Only useful for
+	  kernel devs running KUnit test harness and are not for inclusion
+	  into a production build.
+
+	  For more information on KUnit and unit tests in general please
+	  refer to the KUnit documentation in Documentation/dev-tools/kunit/.