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/uapi/asm-generic/param.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 include/uapi/asm-generic/param.h (limited to 'include/uapi/asm-generic/param.h') diff --git a/include/uapi/asm-generic/param.h b/include/uapi/asm-generic/param.h new file mode 100644 index 000000000..3ed505dfe --- /dev/null +++ b/include/uapi/asm-generic/param.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI__ASM_GENERIC_PARAM_H +#define _UAPI__ASM_GENERIC_PARAM_H + +#ifndef __USER_HZ +#define __USER_HZ 100 +#endif + +#ifndef HZ +#define HZ __USER_HZ +#endif + +#ifndef EXEC_PAGESIZE +#define EXEC_PAGESIZE 4096 +#endif + +#ifndef NOGROUP +#define NOGROUP (-1) +#endif + +#define MAXHOSTNAMELEN 64 /* max length of hostname */ + + +#endif /* _UAPI__ASM_GENERIC_PARAM_H */ -- cgit v1.3.1