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, 95 insertions, 0 deletions

diff --git a/include/trace/events/mce.h b/include/trace/events/mce.h
new file mode 100644
index 000000000..c1c50df9e
--- /dev/null
+++ b/include/trace/events/mce.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mce
+
+#if !defined(_TRACE_MCE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MCE_H
+
+#include <linux/ktime.h>
+#include <linux/tracepoint.h>
+#include <asm/mce.h>
+
+/*
+ * MCE Event Record.
+ *
+ * Only very relevant and transient information which cannot be
+ * gathered from a system by any other means or which can only be
+ * acquired arduously should be added to this record.
+ */
+
+TRACE_EVENT(mce_record,
+
+	TP_PROTO(struct mce_hw_err *err),
+
+	TP_ARGS(err),
+
+	TP_STRUCT__entry(
+		__field(	u64,		mcgcap		)
+		__field(	u64,		mcgstatus	)
+		__field(	u64,		status		)
+		__field(	u64,		addr		)
+		__field(	u64,		misc		)
+		__field(	u64,		synd		)
+		__field(	u64,		ipid		)
+		__field(	u64,		ip		)
+		__field(	u64,		tsc		)
+		__field(	u64,		ppin		)
+		__field(	u64,		walltime	)
+		__field(	u32,		cpu		)
+		__field(	u32,		cpuid		)
+		__field(	u32,		apicid		)
+		__field(	u32,		socketid	)
+		__field(	u8,		cs		)
+		__field(	u8,		bank		)
+		__field(	u8,		cpuvendor	)
+		__field(	u32,		microcode	)
+		__dynamic_array(u8, v_data, sizeof(err->vendor))
+	),
+
+	TP_fast_assign(
+		__entry->mcgcap		= err->m.mcgcap;
+		__entry->mcgstatus	= err->m.mcgstatus;
+		__entry->status		= err->m.status;
+		__entry->addr		= err->m.addr;
+		__entry->misc		= err->m.misc;
+		__entry->synd		= err->m.synd;
+		__entry->ipid		= err->m.ipid;
+		__entry->ip		= err->m.ip;
+		__entry->tsc		= err->m.tsc;
+		__entry->ppin		= err->m.ppin;
+		__entry->walltime	= err->m.time;
+		__entry->cpu		= err->m.extcpu;
+		__entry->cpuid		= err->m.cpuid;
+		__entry->apicid		= err->m.apicid;
+		__entry->socketid	= err->m.socketid;
+		__entry->cs		= err->m.cs;
+		__entry->bank		= err->m.bank;
+		__entry->cpuvendor	= err->m.cpuvendor;
+		__entry->microcode	= err->m.microcode;
+		memcpy(__get_dynamic_array(v_data), &err->vendor, sizeof(err->vendor));
+	),
+
+	TP_printk("CPU: %d, MCGc/s: %llx/%llx, MC%d: %016llx, IPID: %016llx, ADDR: %016llx, MISC: %016llx, SYND: %016llx, RIP: %02x:<%016llx>, TSC: %llx, PPIN: %llx, vendor: %u, CPUID: %x, time: %llu, socket: %u, APIC: %x, microcode: %x, vendor data: %s",
+		__entry->cpu,
+		__entry->mcgcap, __entry->mcgstatus,
+		__entry->bank, __entry->status,
+		__entry->ipid,
+		__entry->addr,
+		__entry->misc,
+		__entry->synd,
+		__entry->cs, __entry->ip,
+		__entry->tsc,
+		__entry->ppin,
+		__entry->cpuvendor,
+		__entry->cpuid,
+		__entry->walltime,
+		__entry->socketid,
+		__entry->apicid,
+		__entry->microcode,
+		__print_dynamic_array(v_data, sizeof(u8)))
+);
+
+#endif /* _TRACE_MCE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>