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, 60 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-fpga-manager b/Documentation/ABI/testing/sysfs-class-fpga-manager
new file mode 100644
index 000000000..d78689c35
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-fpga-manager
@@ -0,0 +1,60 @@
+What:		/sys/class/fpga_manager/<fpga>/name
+Date:		August 2015
+KernelVersion:	4.3
+Contact:	Alan Tull <atull@opensource.altera.com>
+Description:	Name of low level fpga manager driver.
+
+What:		/sys/class/fpga_manager/<fpga>/state
+Date:		August 2015
+KernelVersion:	4.3
+Contact:	Alan Tull <atull@opensource.altera.com>
+Description:	Read fpga manager state as a string.
+		The intent is to provide enough detail that if something goes
+		wrong during FPGA programming (something that the driver can't
+		fix) then userspace can know, i.e. if the firmware request
+		fails, that could be due to not being able to find the firmware
+		file.
+
+		This is a superset of FPGA states and fpga manager driver
+		states.  The fpga manager driver is walking through these steps
+		to get the FPGA into a known operating state.  It's a sequence,
+		though some steps may get skipped.  Valid FPGA states will vary
+		by manufacturer; this is a superset.
+
+		* unknown		= can't determine state
+		* power off		= FPGA power is off
+		* power up		= FPGA reports power is up
+		* reset			= FPGA held in reset state
+		* firmware request	= firmware class request in progress
+		* firmware request error = firmware request failed
+		* write init		= preparing FPGA for programming
+		* write init error	= Error while preparing FPGA for programming
+		* write			= FPGA ready to receive image data
+		* write error		= Error while programming
+		* write complete	= Doing post programming steps
+		* write complete error	= Error while doing post programming
+		* operating		= FPGA is programmed and operating
+
+What:		/sys/class/fpga_manager/<fpga>/status
+Date:		June 2018
+KernelVersion:	4.19
+Contact:	Wu Hao <hao.wu@intel.com>
+Description:	Read fpga manager status as a string.
+		If FPGA programming operation fails, it could be caused by crc
+		error or incompatible bitstream image. The intent of this
+		interface is to provide more detailed information for FPGA
+		programming errors to userspace. This is a list of strings for
+		the supported status.
+
+		* reconfig operation error	- invalid operations detected by
+						  reconfiguration hardware.
+						  e.g. start reconfiguration
+						  with errors not cleared
+		* reconfig CRC error		- CRC error detected by
+						  reconfiguration hardware.
+		* reconfig incompatible image	- reconfiguration image is
+						  incompatible with hardware
+		* reconfig IP protocol error	- protocol errors detected by
+						  reconfiguration hardware
+		* reconfig fifo overflow error	- FIFO overflow detected by
+						  reconfiguration hardware