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-driver-pciback | 28 ++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-driver-pciback (limited to 'Documentation/ABI/testing/sysfs-driver-pciback') diff --git a/Documentation/ABI/testing/sysfs-driver-pciback b/Documentation/ABI/testing/sysfs-driver-pciback new file mode 100644 index 000000000..49f5fd0c8 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-driver-pciback @@ -0,0 +1,28 @@ +What: /sys/bus/pci/drivers/pciback/quirks +Date: Oct 2011 +KernelVersion: 3.1 +Contact: xen-devel@lists.xenproject.org +Description: + If the permissive attribute is set, then writing a string in + the format of DDDD:BB:DD.F-REG:SIZE:MASK will allow the guest + to write and read from the PCI device. That is Domain:Bus: + Device.Function-Register:Size:Mask (Domain is optional). + For example:: + + #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks + + will allow the guest to read and write to the configuration + register 0x0E. + +What: /sys/bus/pci/drivers/pciback/allow_interrupt_control +Date: Jan 2020 +KernelVersion: 5.6 +Contact: xen-devel@lists.xenproject.org +Description: + List of devices which can have interrupt control flag (INTx, + MSI, MSI-X) set by a connected guest. It is meant to be set + only when the guest is a stubdomain hosting device model (qemu) + and the actual device is assigned to a HVM. It is not safe + (similar to permissive attribute) to set for a devices assigned + to a PV guest. The device is automatically removed from this + list when the connected pcifront terminates. -- cgit v1.3.1