From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall 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 Signed-off-by: Stafford Horne --- Documentation/ABI/testing/sysfs-bus-siox | 90 ++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-siox (limited to 'Documentation/ABI/testing/sysfs-bus-siox') diff --git a/Documentation/ABI/testing/sysfs-bus-siox b/Documentation/ABI/testing/sysfs-bus-siox new file mode 100644 index 000000000..50e80238f --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-siox @@ -0,0 +1,90 @@ +What: /sys/bus/siox/devices/siox-X/active +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + On reading represents the current state of the bus. If it + contains a "0" the bus is stopped and connected devices are + expected to not do anything because their watchdog triggered. + When the file contains a "1" the bus is operated and periodically + does a push-pull cycle to write and read data from the + connected devices. + + When writing a "0" or "1" the bus moves to the described state. + +What: /sys/bus/siox/devices/siox-X/device_add +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Write-only file. Write + + + + to add a new device dynamically. is the name that is used to match + to a driver (similar to the platform bus). and define + the length of the input and output shift register in bytes respectively. + + defines the 4 bit device type that is check to identify connection + problems. + + The new device is added to the end of the existing chain. + +What: /sys/bus/siox/devices/siox-X/device_remove +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Write-only file. A single write removes the last device in the siox chain. + +What: /sys/bus/siox/devices/siox-X/poll_interval_ns +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Defines the interval between two poll cycles in nano seconds. + Note this is rounded to jiffies on writing. On reading the current value + is returned. + +What: /sys/bus/siox/devices/siox-X-Y/connected +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Read-only value. "0" means the Yth device on siox bus X isn't "connected" i.e. + communication with it is not ensured. "1" signals a working connection. + +What: /sys/bus/siox/devices/siox-X-Y/inbytes +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Read-only value reporting the inbytes value provided to siox-X/device_add + +What: /sys/bus/siox/devices/siox-X-Y/status_errors +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Counts the number of time intervals when the read status byte doesn't yield the + expected value. + +What: /sys/bus/siox/devices/siox-X-Y/type +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Read-only value reporting the type value provided to siox-X/device_add. + +What: /sys/bus/siox/devices/siox-X-Y/watchdog +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Read-only value reporting if the watchdog of the siox device is + active. "0" means the watchdog is not active and the device is expected to + be operational. "1" means the watchdog keeps the device in reset. + +What: /sys/bus/siox/devices/siox-X-Y/watchdog_errors +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Read-only value reporting the number to time intervals when the + watchdog was active. + +What: /sys/bus/siox/devices/siox-X-Y/outbytes +KernelVersion: 4.16 +Contact: Thorsten Scherer , Uwe Kleine-König +Description: + Read-only value reporting the outbytes value provided to siox-X/device_add. -- cgit v1.3.1