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, 30 insertions, 0 deletions

diff --git a/Documentation/admin-guide/aoe/status.sh b/Documentation/admin-guide/aoe/status.sh
new file mode 100644
index 000000000..eeec7baae
--- /dev/null
+++ b/Documentation/admin-guide/aoe/status.sh
@@ -0,0 +1,30 @@
+#! /bin/sh
+# collate and present sysfs information about AoE storage
+#
+# A more complete version of this script is aoe-stat, in the
+# aoetools.
+
+set -e
+format="%8s\t%8s\t%8s\n"
+me=`basename $0`
+sysd=${sysfs_dir:-/sys}
+
+# printf "$format" device mac netif state
+
+# Suse 9.1 Pro doesn't put /sys in /etc/mtab
+#test -z "`mount | grep sysfs`" && {
+test ! -d "$sysd/block" && {
+	echo "$me Error: sysfs is not mounted" 1>&2
+	exit 1
+}
+
+for d in `ls -d $sysd/block/etherd* 2>/dev/null | grep -v p` end; do
+	# maybe ls comes up empty, so we use "end"
+	test $d = end && continue
+
+	dev=`echo "$d" | sed 's/.*!//'`
+	printf "$format" \
+		"$dev" \
+		"`cat \"$d/netif\"`" \
+		"`cat \"$d/state\"`"
+done | sort