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, 119 insertions, 0 deletions

diff --git a/fs/jffs2/compr.h b/fs/jffs2/compr.h
new file mode 100644
index 000000000..3716b6b79
--- /dev/null
+++ b/fs/jffs2/compr.h
@@ -0,0 +1,119 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2004   Ferenc Havasi <havasi@inf.u-szeged.hu>,
+ *		      University of Szeged, Hungary
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#ifndef __JFFS2_COMPR_H__
+#define __JFFS2_COMPR_H__
+
+#include <linux/kernel.h>
+#include <linux/vmalloc.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/jffs2.h>
+#include "jffs2_fs_i.h"
+#include "jffs2_fs_sb.h"
+#include "nodelist.h"
+
+#define JFFS2_RUBINMIPS_PRIORITY 10
+#define JFFS2_DYNRUBIN_PRIORITY  20
+#define JFFS2_LZARI_PRIORITY     30
+#define JFFS2_RTIME_PRIORITY     50
+#define JFFS2_ZLIB_PRIORITY      60
+#define JFFS2_LZO_PRIORITY       80
+
+
+#define JFFS2_RUBINMIPS_DISABLED /* RUBINs will be used only */
+#define JFFS2_DYNRUBIN_DISABLED  /*	   for decompression */
+
+#define JFFS2_COMPR_MODE_NONE       0
+#define JFFS2_COMPR_MODE_PRIORITY   1
+#define JFFS2_COMPR_MODE_SIZE       2
+#define JFFS2_COMPR_MODE_FAVOURLZO  3
+#define JFFS2_COMPR_MODE_FORCELZO   4
+#define JFFS2_COMPR_MODE_FORCEZLIB  5
+
+#define FAVOUR_LZO_PERCENT 80
+
+struct jffs2_compressor {
+	struct list_head list;
+	int priority;			/* used by prirority comr. mode */
+	char *name;
+	char compr;			/* JFFS2_COMPR_XXX */
+	int (*compress)(unsigned char *data_in, unsigned char *cpage_out,
+			uint32_t *srclen, uint32_t *destlen);
+	int (*decompress)(unsigned char *cdata_in, unsigned char *data_out,
+			  uint32_t cdatalen, uint32_t datalen);
+	int usecount;
+	int disabled;		/* if set the compressor won't compress */
+	unsigned char *compr_buf;	/* used by size compr. mode */
+	uint32_t compr_buf_size;	/* used by size compr. mode */
+	uint32_t stat_compr_orig_size;
+	uint32_t stat_compr_new_size;
+	uint32_t stat_compr_blocks;
+	uint32_t stat_decompr_blocks;
+};
+
+int jffs2_register_compressor(struct jffs2_compressor *comp);
+int jffs2_unregister_compressor(struct jffs2_compressor *comp);
+
+int jffs2_compressors_init(void);
+int jffs2_compressors_exit(void);
+
+uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
+			unsigned char *data_in, unsigned char **cpage_out,
+			uint32_t *datalen, uint32_t *cdatalen);
+
+int jffs2_decompress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
+		     uint16_t comprtype, unsigned char *cdata_in,
+		     unsigned char *data_out, uint32_t cdatalen, uint32_t datalen);
+
+void jffs2_free_comprbuf(unsigned char *comprbuf, unsigned char *orig);
+
+/* Compressor modules */
+/* These functions will be called by jffs2_compressors_init/exit */
+
+#ifdef CONFIG_JFFS2_RUBIN
+int jffs2_rubinmips_init(void);
+void jffs2_rubinmips_exit(void);
+int jffs2_dynrubin_init(void);
+void jffs2_dynrubin_exit(void);
+#else
+static inline int jffs2_rubinmips_init(void) { return 0; }
+static inline void jffs2_rubinmips_exit(void) {}
+static inline int jffs2_dynrubin_init(void) { return 0; }
+static inline void jffs2_dynrubin_exit(void) {}
+#endif
+#ifdef CONFIG_JFFS2_RTIME
+extern int jffs2_rtime_init(void);
+extern void jffs2_rtime_exit(void);
+#else
+static inline int jffs2_rtime_init(void) { return 0; }
+static inline void jffs2_rtime_exit(void) {}
+#endif
+#ifdef CONFIG_JFFS2_ZLIB
+extern int jffs2_zlib_init(void);
+extern void jffs2_zlib_exit(void);
+#else
+static inline int jffs2_zlib_init(void) { return 0; }
+static inline void jffs2_zlib_exit(void) {}
+#endif
+#ifdef CONFIG_JFFS2_LZO
+extern int jffs2_lzo_init(void);
+extern void jffs2_lzo_exit(void);
+#else
+static inline int jffs2_lzo_init(void) { return 0; }
+static inline void jffs2_lzo_exit(void) {}
+#endif
+
+#endif /* __JFFS2_COMPR_H__ */