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 --- arch/mips/generic/vmlinux.its.S | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 arch/mips/generic/vmlinux.its.S (limited to 'arch/mips/generic/vmlinux.its.S') diff --git a/arch/mips/generic/vmlinux.its.S b/arch/mips/generic/vmlinux.its.S new file mode 100644 index 000000000..3e2546765 --- /dev/null +++ b/arch/mips/generic/vmlinux.its.S @@ -0,0 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/dts-v1/; + +/ { + description = KERNEL_NAME; + #address-cells = ; + + images { + kernel { + description = KERNEL_NAME; + data = /incbin/(VMLINUX_BINARY); + type = "kernel"; + arch = "mips"; + os = "linux"; + compression = VMLINUX_COMPRESSION; + load = /bits/ ADDR_BITS ; + entry = /bits/ ADDR_BITS ; + hash { + algo = "sha1"; + }; + }; + }; + + configurations { + default = "conf-default"; + + conf-default { + description = "Generic Linux kernel"; + kernel = "kernel"; + }; + }; +}; -- cgit v1.3.1