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, 41 insertions, 0 deletions

diff --git a/net/Kconfig.debug b/net/Kconfig.debug
new file mode 100644
index 000000000..277fab8c4
--- /dev/null
+++ b/net/Kconfig.debug
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config NET_DEV_REFCNT_TRACKER
+	bool "Enable net device refcount tracking"
+	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT && NET
+	select REF_TRACKER
+	default n
+	help
+	  Enable debugging feature to track device references.
+	  This adds memory and cpu costs.
+
+config NET_NS_REFCNT_TRACKER
+	bool "Enable networking namespace refcount tracking"
+	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT && NET
+	select REF_TRACKER
+	default n
+	help
+	  Enable debugging feature to track netns references.
+	  This adds memory and cpu costs.
+
+config DEBUG_NET
+	bool "Add generic networking debug"
+	depends on DEBUG_KERNEL && NET
+	help
+	  Enable extra sanity checks in networking.
+	  This is mostly used by fuzzers, but is safe to select.
+
+config DEBUG_NET_SMALL_RTNL
+	bool "Add extra per-netns mutex inside RTNL"
+	depends on DEBUG_KERNEL && NET && LOCK_DEBUGGING_SUPPORT
+	select PROVE_LOCKING
+	default n
+	help
+	  rtnl_lock() is being replaced with rtnl_net_lock() that
+	  acquires the global RTNL and a small per-netns RTNL mutex.
+
+	  During the conversion, rtnl_net_lock() just adds an extra
+	  mutex in every RTNL scope and slows down the operations.
+
+	  Once the conversion completes, rtnl_lock() will be removed
+	  and rtnetlink will gain per-netns scalability.