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-class-rnbd-server | 58 +++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-rnbd-server (limited to 'Documentation/ABI/testing/sysfs-class-rnbd-server') diff --git a/Documentation/ABI/testing/sysfs-class-rnbd-server b/Documentation/ABI/testing/sysfs-class-rnbd-server new file mode 100644 index 000000000..6c5996cd7 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-rnbd-server @@ -0,0 +1,58 @@ +What: /sys/class/rnbd-server +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: provide information about RNBD-server. + +What: /sys/class/rnbd-server/ctl/ +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: When a client maps a device, a directory entry with the name of the + block device is created under /sys/class/rnbd-server/ctl/devices/. + +What: /sys/class/rnbd-server/ctl/devices//block_dev +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Is a symlink to the sysfs entry of the exported device. + + Example: + block_dev -> ../../../../class/block/ram0 + +What: /sys/class/rnbd-server/ctl/devices//sessions/ +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: For each client a particular device is exported to, following directory will be + created: + + /sys/class/rnbd-server/ctl/devices//sessions// + + When the device is unmapped by that client, the directory will be removed. + +What: /sys/class/rnbd-server/ctl/devices//sessions//read_only +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains '1' if device is mapped read-only, otherwise '0'. + +What: /sys/class/rnbd-server/ctl/devices//sessions//mapping_path +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains the relative device path provided by the user during mapping. + +What: /sys/class/rnbd-server/ctl/devices//sessions//access_mode +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains the device access mode: ro, rw or migration. + +What: /sys/class/rnbd-server/ctl/devices//sessions//force_close +Date: Nov 2020 +KernelVersion: 5.10 +Contact: Jack Wang Danil Kipnis +Description: Write "1" to the file to close the device on server side. Please + note that the client side device will not be closed, read or + write to the device will get -ENOTCONN. -- cgit v1.3.1