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, 36 insertions, 0 deletions

diff --git a/drivers/scsi/fcoe/libfcoe.h b/drivers/scsi/fcoe/libfcoe.h
new file mode 100644
index 000000000..b8bdfab51
--- /dev/null
+++ b/drivers/scsi/fcoe/libfcoe.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _FCOE_LIBFCOE_H_
+#define _FCOE_LIBFCOE_H_
+
+extern unsigned int libfcoe_debug_logging;
+#define LIBFCOE_LOGGING	          0x01 /* General logging, not categorized */
+#define LIBFCOE_FIP_LOGGING       0x02 /* FIP logging */
+#define LIBFCOE_TRANSPORT_LOGGING 0x04 /* FCoE transport logging */
+#define LIBFCOE_SYSFS_LOGGING     0x08 /* fcoe_sysfs logging */
+
+#define LIBFCOE_CHECK_LOGGING(LEVEL, CMD)		\
+do {							\
+	if (unlikely(libfcoe_debug_logging & LEVEL))	\
+		do {					\
+			CMD;				\
+		} while (0);				\
+} while (0)
+
+#define LIBFCOE_DBG(fmt, args...)					\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_LOGGING,				\
+			      pr_info("libfcoe: " fmt, ##args);)
+
+#define LIBFCOE_FIP_DBG(fip, fmt, args...)				\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_FIP_LOGGING,			\
+			      pr_info("host%d: fip: " fmt,		\
+				      (fip)->lp->host->host_no, ##args);)
+
+#define LIBFCOE_TRANSPORT_DBG(fmt, args...)				\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_TRANSPORT_LOGGING,		\
+			      pr_info("%s: " fmt, __func__, ##args);)
+
+#define LIBFCOE_SYSFS_DBG(cdev, fmt, args...)				\
+	LIBFCOE_CHECK_LOGGING(LIBFCOE_SYSFS_LOGGING,			\
+			      pr_info("ctlr_%d: " fmt, cdev->id, ##args);)
+
+#endif /* _FCOE_LIBFCOE_H_ */