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/x86/boot/cpuflags.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 arch/x86/boot/cpuflags.h (limited to 'arch/x86/boot/cpuflags.h') diff --git a/arch/x86/boot/cpuflags.h b/arch/x86/boot/cpuflags.h new file mode 100644 index 000000000..a398d9204 --- /dev/null +++ b/arch/x86/boot/cpuflags.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef BOOT_CPUFLAGS_H +#define BOOT_CPUFLAGS_H + +#include +#include + +struct cpu_features { + int level; /* Family, or 64 for x86-64 */ + int family; /* Family, always */ + int model; + u32 flags[NCAPINTS]; +}; + +extern struct cpu_features cpu; +extern u32 cpu_vendor[3]; + +#ifdef CONFIG_X86_32 +bool has_eflag(unsigned long mask); +#else +static inline bool has_eflag(unsigned long mask) { return true; } +#endif +void get_cpuflags(void); +void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d); +bool has_cpuflag(int flag); + +#endif -- cgit v1.3.1