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, 63 insertions, 0 deletions

diff --git a/fs/gfs2/log.h b/fs/gfs2/log.h
new file mode 100644
index 000000000..10beda624
--- /dev/null
+++ b/fs/gfs2/log.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+ */
+
+#ifndef __LOG_DOT_H__
+#define __LOG_DOT_H__
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/writeback.h>
+#include "incore.h"
+#include "inode.h"
+
+/*
+ * The minimum amount of log space required for a log flush is one block for
+ * revokes and one block for the log header.  Log flushes other than
+ * GFS2_LOG_HEAD_FLUSH_NORMAL may write one or two more log headers.
+ */
+#define GFS2_LOG_FLUSH_MIN_BLOCKS 4
+
+static inline void gfs2_ordered_add_inode(struct gfs2_inode *ip)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+
+	if (gfs2_is_jdata(ip) || !gfs2_is_ordered(sdp))
+		return;
+
+	if (list_empty(&ip->i_ordered)) {
+		spin_lock(&sdp->sd_ordered_lock);
+		if (list_empty(&ip->i_ordered))
+			list_add(&ip->i_ordered, &sdp->sd_log_ordered);
+		spin_unlock(&sdp->sd_ordered_lock);
+	}
+}
+
+void gfs2_ordered_del_inode(struct gfs2_inode *ip);
+unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct);
+bool gfs2_log_is_empty(struct gfs2_sbd *sdp);
+void gfs2_log_release_revokes(struct gfs2_sbd *sdp, unsigned int revokes);
+void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks);
+bool gfs2_log_try_reserve(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
+			  unsigned int *extra_revokes);
+void gfs2_log_reserve(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
+		      unsigned int *extra_revokes);
+void gfs2_write_log_header(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd,
+			   u64 seq, u32 tail, u32 lblock, u32 flags,
+			   blk_opf_t op_flags);
+void gfs2_remove_from_journal(struct buffer_head *bh, int meta);
+void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl,
+		    u32 type);
+void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *trans);
+void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc);
+void log_flush_wait(struct gfs2_sbd *sdp);
+
+int gfs2_logd(void *data);
+void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd);
+void gfs2_glock_remove_revoke(struct gfs2_glock *gl);
+void gfs2_flush_revokes(struct gfs2_sbd *sdp);
+void gfs2_ail_drain(struct gfs2_sbd *sdp);
+
+#endif /* __LOG_DOT_H__ */