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/alpha/boot/bootloader.lds | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 arch/alpha/boot/bootloader.lds (limited to 'arch/alpha/boot/bootloader.lds') diff --git a/arch/alpha/boot/bootloader.lds b/arch/alpha/boot/bootloader.lds new file mode 100644 index 000000000..8cdff54c6 --- /dev/null +++ b/arch/alpha/boot/bootloader.lds @@ -0,0 +1,25 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +OUTPUT_FORMAT("elf64-alpha") +ENTRY(__start) +printk = srm_printk; +SECTIONS +{ + . = 0x20000000; + .text : { *(.text) } + _etext = .; + PROVIDE (etext = .); + .rodata : { *(.rodata) *(.rodata.*) } + .data : { *(.data) CONSTRUCTORS } + .got : { *(.got) } + .sdata : { *(.sdata) } + _edata = .; + PROVIDE (edata = .); + .sbss : { *(.sbss) *(.scommon) } + .bss : { *(.bss) *(COMMON) } + _end = . ; + PROVIDE (end = .); + + .mdebug 0 : { *(.mdebug) } + .note 0 : { *(.note) } + .comment 0 : { *(.comment) } +} -- cgit v1.3.1