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, 78 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/debugfs-cros-ec b/Documentation/ABI/testing/debugfs-cros-ec
new file mode 100644
index 000000000..9a040c6f5
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-cros-ec
@@ -0,0 +1,78 @@
+What:		/sys/kernel/debug/<cros-ec-device>/console_log
+Date:		September 2017
+KernelVersion:	4.13
+Description:
+		If the EC supports the CONSOLE_READ command type, this file
+		can be used to grab the EC logs. The kernel polls for the log
+		and keeps its own buffer but userspace should grab this and
+		write it out to some logs.
+
+What:		/sys/kernel/debug/<cros-ec-device>/panicinfo
+Date:		September 2017
+KernelVersion:	4.13
+Description:
+		This file dumps the EC panic information from the previous
+		reboot. This file will only exist if the PANIC_INFO command
+		type is supported by the EC.
+
+What:		/sys/kernel/debug/<cros-ec-device>/pdinfo
+Date:		June 2018
+KernelVersion:	4.17
+Description:
+		This file provides the port role, muxes and power debug
+		information for all the USB PD/type-C ports available. If
+		the are no ports available, this file will be just an empty
+		file.
+
+What:		/sys/kernel/debug/<cros-ec-device>/uptime
+Date:		June 2019
+KernelVersion:	5.3
+Description:
+		A u32 providing the time since EC booted in ms. This is
+		is used for synchronizing the AP host time with the EC
+		log. An error is returned if the command is not supported
+		by the EC or there is a communication problem.
+
+What:		/sys/kernel/debug/<cros-ec-device>/last_resume_result
+Date:		June 2019
+KernelVersion:	5.3
+Description:
+		Some ECs have a feature where they will track transitions to
+		the (Intel) processor's SLP_S0 line, in order to detect cases
+		where a system failed to go into S0ix. When the system resumes,
+		an EC with this feature will return a summary of SLP_S0
+		transitions that occurred. The last_resume_result file returns
+		the most recent response from the AP's resume message to the EC.
+
+		The bottom 31 bits contain a count of the number of SLP_S0
+		transitions that occurred since the suspend message was
+		received. Bit 31 is set if the EC attempted to wake the
+		system due to a timeout when watching for SLP_S0 transitions.
+		Callers can use this to detect a wake from the EC due to
+		S0ix timeouts. The result will be zero if no suspend
+		transitions have been attempted, or the EC does not support
+		this feature.
+
+		Output will be in the format: "0x%08x\n".
+
+What:		/sys/kernel/debug/<cros-ec-device>/suspend_timeout_ms
+Date:		August 2022
+KernelVersion:	6.1
+Description:
+		Some ECs have a feature where they will track transitions of
+		a hardware-controlled sleep line, such as Intel's SLP_S0 line,
+		in order to detect cases where a system failed to go into deep
+		sleep states. The suspend_timeout_ms file controls the amount of
+		time in milliseconds the EC will wait before declaring a sleep
+		timeout event and attempting to wake the system.
+
+		Supply 0 to use the default value coded into EC firmware. Supply
+		65535 (EC_HOST_SLEEP_TIMEOUT_INFINITE) to disable the EC sleep
+		failure detection mechanism. Values in between 0 and 65535
+		indicate the number of milliseconds the EC should wait after a
+		sleep transition before declaring a timeout. This includes both
+		the duration after a sleep command was received but before the
+		hardware line changed, as well as the duration between when the
+		hardware line changed and the kernel sent an EC resume command.
+
+		Output will be in the format: "%u\n".