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/lib/cache-smp.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 arch/x86/lib/cache-smp.c (limited to 'arch/x86/lib/cache-smp.c') diff --git a/arch/x86/lib/cache-smp.c b/arch/x86/lib/cache-smp.c new file mode 100644 index 000000000..7d3edd6de --- /dev/null +++ b/arch/x86/lib/cache-smp.c @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +static void __wbinvd(void *dummy) +{ + wbinvd(); +} + +void wbinvd_on_cpu(int cpu) +{ + smp_call_function_single(cpu, __wbinvd, NULL, 1); +} +EXPORT_SYMBOL_FOR_KVM(wbinvd_on_cpu); + +void wbinvd_on_all_cpus(void) +{ + on_each_cpu(__wbinvd, NULL, 1); +} +EXPORT_SYMBOL(wbinvd_on_all_cpus); + +void wbinvd_on_cpus_mask(struct cpumask *cpus) +{ + on_each_cpu_mask(cpus, __wbinvd, NULL, 1); +} +EXPORT_SYMBOL_FOR_KVM(wbinvd_on_cpus_mask); + +static void __wbnoinvd(void *dummy) +{ + wbnoinvd(); +} + +void wbnoinvd_on_all_cpus(void) +{ + on_each_cpu(__wbnoinvd, NULL, 1); +} +EXPORT_SYMBOL_FOR_KVM(wbnoinvd_on_all_cpus); + +void wbnoinvd_on_cpus_mask(struct cpumask *cpus) +{ + on_each_cpu_mask(cpus, __wbnoinvd, NULL, 1); +} +EXPORT_SYMBOL_FOR_KVM(wbnoinvd_on_cpus_mask); -- cgit v1.3.1