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, 91 insertions, 0 deletions

diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
new file mode 100644
index 000000000..49bb1aaa8
--- /dev/null
+++ b/block/blk-mq-debugfs.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef INT_BLK_MQ_DEBUGFS_H
+#define INT_BLK_MQ_DEBUGFS_H
+
+#ifdef CONFIG_BLK_DEBUG_FS
+
+#include <linux/seq_file.h>
+
+struct blk_mq_hw_ctx;
+
+struct blk_mq_debugfs_attr {
+	const char *name;
+	umode_t mode;
+	int (*show)(void *, struct seq_file *);
+	ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
+	/* Set either .show or .seq_ops. */
+	const struct seq_operations *seq_ops;
+};
+
+int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq);
+int blk_mq_debugfs_rq_show(struct seq_file *m, void *v);
+
+void blk_mq_debugfs_register(struct request_queue *q);
+void blk_mq_debugfs_register_hctx(struct request_queue *q,
+				  struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_register_hctxs(struct request_queue *q);
+void blk_mq_debugfs_unregister_hctxs(struct request_queue *q);
+
+void blk_mq_debugfs_register_sched(struct request_queue *q);
+void blk_mq_debugfs_unregister_sched(struct request_queue *q);
+void blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
+				       struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx);
+
+void blk_mq_debugfs_register_rq_qos(struct request_queue *q);
+#else
+static inline void blk_mq_debugfs_register(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_register_hctx(struct request_queue *q,
+						struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_register_hctxs(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_register_sched(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_sched(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
+						      struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_register_rq_qos(struct request_queue *q)
+{
+}
+
+#endif
+
+#if defined(CONFIG_BLK_DEV_ZONED) && defined(CONFIG_BLK_DEBUG_FS)
+int queue_zone_wplugs_show(void *data, struct seq_file *m);
+#else
+static inline int queue_zone_wplugs_show(void *data, struct seq_file *m)
+{
+	return 0;
+}
+#endif
+
+#endif