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, 44 insertions, 0 deletions

diff --git a/net/sunrpc/netns.h b/net/sunrpc/netns.h
new file mode 100644
index 000000000..4efb5f28d
--- /dev/null
+++ b/net/sunrpc/netns.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __SUNRPC_NETNS_H__
+#define __SUNRPC_NETNS_H__
+
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+
+struct cache_detail;
+
+struct sunrpc_net {
+	struct proc_dir_entry *proc_net_rpc;
+	struct cache_detail *ip_map_cache;
+	struct cache_detail *unix_gid_cache;
+	struct cache_detail *rsc_cache;
+	struct cache_detail *rsi_cache;
+
+	struct super_block *pipefs_sb;
+	struct rpc_pipe *gssd_dummy;
+	struct mutex pipefs_sb_lock;
+
+	struct list_head all_clients;
+	spinlock_t rpc_client_lock;
+
+	struct rpc_clnt *rpcb_local_clnt;
+	struct rpc_clnt *rpcb_local_clnt4;
+	spinlock_t rpcb_clnt_lock;
+	unsigned int rpcb_users;
+	unsigned int rpcb_is_af_local : 1;
+
+	struct mutex gssp_lock;
+	struct rpc_clnt *gssp_clnt;
+	int use_gss_proxy;
+	int pipe_version;
+	atomic_t pipe_users;
+	struct proc_dir_entry *use_gssp_proc;
+	struct proc_dir_entry *gss_krb5_enctypes;
+};
+
+extern unsigned int sunrpc_net_id;
+
+int ip_map_cache_create(struct net *);
+void ip_map_cache_destroy(struct net *);
+
+#endif