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, 85 insertions, 0 deletions

diff --git a/fs/dlm/lock.h b/fs/dlm/lock.h
new file mode 100644
index 000000000..b23d7b854
--- /dev/null
+++ b/fs/dlm/lock.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) 2005-2007 Red Hat, Inc.  All rights reserved.
+**
+**
+*******************************************************************************
+******************************************************************************/
+
+#ifndef __LOCK_DOT_H__
+#define __LOCK_DOT_H__
+
+void dlm_dump_rsb(struct dlm_rsb *r);
+void dlm_dump_rsb_name(struct dlm_ls *ls, const char *name, int len);
+void dlm_print_lkb(struct dlm_lkb *lkb);
+void dlm_receive_message_saved(struct dlm_ls *ls, const struct dlm_message *ms,
+			       uint32_t saved_seq);
+void dlm_receive_buffer(const union dlm_packet *p, int nodeid);
+int dlm_modes_compat(int mode1, int mode2);
+void free_inactive_rsb(struct dlm_rsb *r);
+void dlm_put_rsb(struct dlm_rsb *r);
+void dlm_hold_rsb(struct dlm_rsb *r);
+int dlm_put_lkb(struct dlm_lkb *lkb);
+int dlm_lock_recovery_try(struct dlm_ls *ls);
+void dlm_lock_recovery(struct dlm_ls *ls);
+void dlm_unlock_recovery(struct dlm_ls *ls);
+void dlm_rsb_scan(struct timer_list *timer);
+void resume_scan_timer(struct dlm_ls *ls);
+
+int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, const char *name,
+		      int len, unsigned int flags, int *r_nodeid, int *result);
+
+int dlm_search_rsb_tree(struct rhashtable *rhash, const void *name, int len,
+			struct dlm_rsb **r_ret);
+
+void dlm_recover_purge(struct dlm_ls *ls, const struct list_head *root_list);
+void dlm_purge_mstcpy_locks(struct dlm_rsb *r);
+void dlm_recover_grant(struct dlm_ls *ls);
+int dlm_recover_waiters_post(struct dlm_ls *ls);
+void dlm_recover_waiters_pre(struct dlm_ls *ls);
+int dlm_recover_master_copy(struct dlm_ls *ls, const struct dlm_rcom *rc,
+			    __le32 *rl_remid, __le32 *rl_result);
+int dlm_recover_process_copy(struct dlm_ls *ls, const struct dlm_rcom *rc,
+			     uint64_t seq);
+
+int dlm_user_request(struct dlm_ls *ls, struct dlm_user_args *ua, int mode,
+	uint32_t flags, void *name, unsigned int namelen);
+int dlm_user_convert(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
+	int mode, uint32_t flags, uint32_t lkid, char *lvb_in);
+int dlm_user_adopt_orphan(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
+	int mode, uint32_t flags, void *name, unsigned int namelen,
+	uint32_t *lkid);
+int dlm_user_unlock(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
+	uint32_t flags, uint32_t lkid, char *lvb_in);
+int dlm_user_cancel(struct dlm_ls *ls,  struct dlm_user_args *ua_tmp,
+	uint32_t flags, uint32_t lkid);
+int dlm_user_purge(struct dlm_ls *ls, struct dlm_user_proc *proc,
+	int nodeid, int pid);
+int dlm_user_deadlock(struct dlm_ls *ls, uint32_t flags, uint32_t lkid);
+void dlm_clear_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc);
+int dlm_debug_add_lkb(struct dlm_ls *ls, uint32_t lkb_id, char *name, int len,
+		      int lkb_nodeid, unsigned int lkb_flags, int lkb_status);
+int dlm_debug_add_lkb_to_waiters(struct dlm_ls *ls, uint32_t lkb_id,
+				 int mstype, int to_nodeid);
+
+static inline int is_master(struct dlm_rsb *r)
+{
+	WARN_ON_ONCE(r->res_nodeid == -1);
+
+	return !r->res_nodeid;
+}
+
+static inline void lock_rsb(struct dlm_rsb *r)
+{
+	spin_lock_bh(&r->res_lock);
+}
+
+static inline void unlock_rsb(struct dlm_rsb *r)
+{
+	spin_unlock_bh(&r->res_lock);
+}
+
+#endif
+