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, 22 insertions, 0 deletions

diff --git a/fs/jffs2/Makefile b/fs/jffs2/Makefile
new file mode 100644
index 000000000..5294969d5
--- /dev/null
+++ b/fs/jffs2/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux Journalling Flash File System v2 (JFFS2)
+#
+#
+
+obj-$(CONFIG_JFFS2_FS) += jffs2.o
+
+jffs2-y	:= compr.o dir.o file.o ioctl.o nodelist.o malloc.o
+jffs2-y	+= read.o nodemgmt.o readinode.o write.o scan.o gc.o
+jffs2-y	+= symlink.o build.o erase.o background.o fs.o writev.o
+jffs2-y	+= super.o debug.o
+
+jffs2-$(CONFIG_JFFS2_FS_WRITEBUFFER)	+= wbuf.o
+jffs2-$(CONFIG_JFFS2_FS_XATTR)		+= xattr.o xattr_trusted.o xattr_user.o
+jffs2-$(CONFIG_JFFS2_FS_SECURITY)	+= security.o
+jffs2-$(CONFIG_JFFS2_FS_POSIX_ACL)	+= acl.o
+jffs2-$(CONFIG_JFFS2_RUBIN)	+= compr_rubin.o
+jffs2-$(CONFIG_JFFS2_RTIME)	+= compr_rtime.o
+jffs2-$(CONFIG_JFFS2_ZLIB)	+= compr_zlib.o
+jffs2-$(CONFIG_JFFS2_LZO)	+= compr_lzo.o
+jffs2-$(CONFIG_JFFS2_SUMMARY)   += summary.o