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, 49 insertions, 0 deletions

diff --git a/fs/smb/server/glob.h b/fs/smb/server/glob.h
new file mode 100644
index 000000000..4ea187af2
--- /dev/null
+++ b/fs/smb/server/glob.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2016 Namjae Jeon <linkinjeon@kernel.org>
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __KSMBD_GLOB_H
+#define __KSMBD_GLOB_H
+
+#include <linux/ctype.h>
+
+#include "unicode.h"
+#include "vfs_cache.h"
+
+extern int ksmbd_debug_types;
+
+#define KSMBD_DEBUG_SMB		BIT(0)
+#define KSMBD_DEBUG_AUTH	BIT(1)
+#define KSMBD_DEBUG_VFS		BIT(2)
+#define KSMBD_DEBUG_OPLOCK      BIT(3)
+#define KSMBD_DEBUG_IPC         BIT(4)
+#define KSMBD_DEBUG_CONN        BIT(5)
+#define KSMBD_DEBUG_RDMA        BIT(6)
+#define KSMBD_DEBUG_ALL         (KSMBD_DEBUG_SMB | KSMBD_DEBUG_AUTH |	\
+				KSMBD_DEBUG_VFS | KSMBD_DEBUG_OPLOCK |	\
+				KSMBD_DEBUG_IPC | KSMBD_DEBUG_CONN |	\
+				KSMBD_DEBUG_RDMA)
+
+#ifdef pr_fmt
+#undef pr_fmt
+#endif
+
+#ifdef SUBMOD_NAME
+#define pr_fmt(fmt)	"ksmbd: " SUBMOD_NAME ": " fmt
+#else
+#define pr_fmt(fmt)	"ksmbd: " fmt
+#endif
+
+#define ksmbd_debug(type, fmt, ...)				\
+	do {							\
+		if (ksmbd_debug_types & KSMBD_DEBUG_##type)	\
+			pr_info(fmt, ##__VA_ARGS__);		\
+	} while (0)
+
+#define UNICODE_LEN(x)		((x) * 2)
+
+#define KSMBD_DEFAULT_GFP	(GFP_KERNEL | __GFP_RETRY_MAYFAIL)
+
+#endif /* __KSMBD_GLOB_H */