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-vfio-mdev | 113 ++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-vfio-mdev (limited to 'Documentation/ABI/testing/sysfs-bus-vfio-mdev') diff --git a/Documentation/ABI/testing/sysfs-bus-vfio-mdev b/Documentation/ABI/testing/sysfs-bus-vfio-mdev new file mode 100644 index 000000000..59fc80426 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-vfio-mdev @@ -0,0 +1,113 @@ +What: /sys/...//mdev_supported_types/ +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory contains list of directories of currently + supported mediated device types and their details for + . Supported type attributes are defined by the + vendor driver who registers with Mediated device framework. + Each supported type is a directory whose name is created + by adding the device driver string as a prefix to the + string provided by the vendor driver. + +What: /sys/...//mdev_supported_types// +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory gives details of supported type, like name, + description, available_instances, device_api etc. + 'device_api' and 'available_instances' are mandatory + attributes to be provided by vendor driver. 'name', + 'description' and other vendor driver specific attributes + are optional. + +What: /sys/.../mdev_supported_types//create +Date: October 2016 +Contact: Kirti Wankhede +Description: + Writing UUID to this file will create mediated device of + type for parent device . This is a + write-only file. + For example:: + + # echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > \ + /sys/devices/foo/mdev_supported_types/foo-1/create + +What: /sys/.../mdev_supported_types//devices/ +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory contains symbolic links pointing to mdev + devices sysfs entries which are created of this . + +What: /sys/.../mdev_supported_types//available_instances +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show the number of mediated + devices of type that can be created. This is a + readonly file. +Users: + Userspace applications interested in creating mediated + device of that type. Userspace application should check + the number of available instances could be created before + creating mediated device of this type. + +What: /sys/.../mdev_supported_types//device_api +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show VFIO device API supported + by this type. For example, "vfio-pci" for a PCI device, + "vfio-platform" for platform device. + +What: /sys/.../mdev_supported_types//name +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show human readable name of the + mediated device that will get created of type . + This is optional attribute. For example: "Grid M60-0Q" +Users: + Userspace applications interested in knowing the name of + a particular that can help in understanding the + type of mediated device. + +What: /sys/.../mdev_supported_types//description +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show description of the type of + mediated device that will get created of type . + This is optional attribute. For example: + "2 heads, 512M FB, 2560x1600 maximum resolution" +Users: + Userspace applications interested in knowing the details of + a particular that can help in understanding the + features provided by that type of mediated device. + +What: /sys/.../// +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory represents device directory of mediated + device. It contains all the attributes related to mediated + device. + +What: /sys/...///mdev_type +Date: October 2016 +Contact: Kirti Wankhede +Description: + This is symbolic link pointing to supported type, + directory of which this mediated device is created. + +What: /sys/...///remove +Date: October 2016 +Contact: Kirti Wankhede +Description: + Writing '1' to this file destroys the mediated device. The + vendor driver can fail the remove() callback if that device + is active and the vendor driver doesn't support hot unplug. + Example:: + + # echo 1 > /sys/bus/mdev/devices//remove -- cgit v1.3.1