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 --- include/trace/events/exceptions.h | 43 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 include/trace/events/exceptions.h (limited to 'include/trace/events/exceptions.h') diff --git a/include/trace/events/exceptions.h b/include/trace/events/exceptions.h new file mode 100644 index 000000000..a631f8de8 --- /dev/null +++ b/include/trace/events/exceptions.h @@ -0,0 +1,43 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM exceptions + +#if !defined(_TRACE_PAGE_FAULT_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_PAGE_FAULT_H + +#include + +DECLARE_EVENT_CLASS(exceptions, + + TP_PROTO(unsigned long address, struct pt_regs *regs, + unsigned long error_code), + + TP_ARGS(address, regs, error_code), + + TP_STRUCT__entry( + __field( unsigned long, address ) + __field( unsigned long, ip ) + __field( unsigned long, error_code ) + ), + + TP_fast_assign( + __entry->address = address; + __entry->ip = instruction_pointer(regs); + __entry->error_code = error_code; + ), + + TP_printk("address=%ps ip=%ps error_code=0x%lx", + (void *)__entry->address, (void *)__entry->ip, + __entry->error_code) ); + +DEFINE_EVENT(exceptions, page_fault_user, + TP_PROTO(unsigned long address, struct pt_regs *regs, unsigned long error_code), + TP_ARGS(address, regs, error_code)); +DEFINE_EVENT(exceptions, page_fault_kernel, + TP_PROTO(unsigned long address, struct pt_regs *regs, unsigned long error_code), + TP_ARGS(address, regs, error_code)); + +#endif /* _TRACE_PAGE_FAULT_H */ + +/* This part must be outside protection */ +#include -- cgit v1.3.1