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, 52 insertions, 0 deletions

diff --git a/tools/perf/util/dsos.h b/tools/perf/util/dsos.h
new file mode 100644
index 000000000..a26774950
--- /dev/null
+++ b/tools/perf/util/dsos.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_DSOS
+#define __PERF_DSOS
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include "rwsem.h"
+
+struct dso;
+struct dso_id;
+struct kmod_path;
+struct machine;
+
+/*
+ * Collection of DSOs as an array for iteration speed, but sorted for O(n)
+ * lookup.
+ */
+struct dsos {
+	struct rw_semaphore lock;
+	struct dso **dsos;
+	unsigned int cnt;
+	unsigned int allocated;
+	bool sorted;
+};
+
+void dsos__init(struct dsos *dsos);
+void dsos__exit(struct dsos *dsos);
+
+int __dsos__add(struct dsos *dsos, struct dso *dso);
+int dsos__add(struct dsos *dsos, struct dso *dso);
+struct dso *dsos__find(struct dsos *dsos, const char *name, bool cmp_short);
+
+struct dso *dsos__findnew_id(struct dsos *dsos, const char *name, const struct dso_id *id);
+ 
+bool dsos__read_build_ids(struct dsos *dsos, bool with_hits);
+
+size_t dsos__fprintf_buildid(struct dsos *dsos, FILE *fp,
+			       bool (skip)(struct dso *dso, int parm), int parm);
+size_t dsos__fprintf(struct dsos *dsos, FILE *fp);
+
+int dsos__hit_all(struct dsos *dsos);
+
+struct dso *dsos__findnew_module_dso(struct dsos *dsos, struct machine *machine,
+				     struct kmod_path *m, const char *filename);
+
+struct dso *dsos__find_kernel_dso(struct dsos *dsos);
+
+int dsos__for_each_dso(struct dsos *dsos, int (*cb)(struct dso *dso, void *data), void *data);
+
+#endif /* __PERF_DSOS */