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/Kconfig.debug | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 arch/alpha/Kconfig.debug (limited to 'arch/alpha/Kconfig.debug') diff --git a/arch/alpha/Kconfig.debug b/arch/alpha/Kconfig.debug new file mode 100644 index 000000000..f85f4281c --- /dev/null +++ b/arch/alpha/Kconfig.debug @@ -0,0 +1,38 @@ +# SPDX-License-Identifier: GPL-2.0 + +config EARLY_PRINTK + bool + depends on ALPHA_GENERIC || ALPHA_SRM + default y + +config ALPHA_LEGACY_START_ADDRESS + bool "Legacy kernel start address" + depends on ALPHA_GENERIC + default n + help + The 2.4 kernel changed the kernel start address from 0x310000 + to 0x810000 to make room for the Wildfire's larger SRM console. + Recent consoles on Titan and Marvel machines also require the + extra room. + + If you're using aboot 0.7 or later, the bootloader will examine the + ELF headers to determine where to transfer control. Unfortunately, + most older bootloaders -- APB or MILO -- hardcoded the kernel start + address rather than examining the ELF headers, and the result is a + hard lockup. + + Say Y if you have a broken bootloader. Say N if you do not, or if + you wish to run on Wildfire, Titan, or Marvel. + +config ALPHA_LEGACY_START_ADDRESS + bool + depends on !ALPHA_GENERIC && !ALPHA_TITAN && !ALPHA_MARVEL && !ALPHA_WILDFIRE + default y + +config MATHEMU + tristate "Kernel FP software completion" if DEBUG_KERNEL && !SMP + default y if !DEBUG_KERNEL || SMP + help + This option is required for IEEE compliant floating point arithmetic + on the Alpha. The only time you would ever not say Y is to say M in + order to debug the code. Say Y unless you know what you are doing. -- cgit v1.3.1