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/powerpc/sysdev/dart.h | 64 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 arch/powerpc/sysdev/dart.h (limited to 'arch/powerpc/sysdev/dart.h') diff --git a/arch/powerpc/sysdev/dart.h b/arch/powerpc/sysdev/dart.h new file mode 100644 index 000000000..7f5df03d3 --- /dev/null +++ b/arch/powerpc/sysdev/dart.h @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) 2004 Olof Johansson , IBM Corporation + */ + +#ifndef _POWERPC_SYSDEV_DART_H +#define _POWERPC_SYSDEV_DART_H + + +/* Offset from base to control register */ +#define DART_CNTL 0 + +/* Offset from base to exception register */ +#define DART_EXCP_U3 0x10 +/* Offset from base to TLB tag registers */ +#define DART_TAGS_U3 0x1000 + +/* U4 registers */ +#define DART_BASE_U4 0x10 +#define DART_SIZE_U4 0x20 +#define DART_EXCP_U4 0x30 +#define DART_TAGS_U4 0x1000 + +/* Control Register fields */ + +/* U3 registers */ +#define DART_CNTL_U3_BASE_MASK 0xfffff +#define DART_CNTL_U3_BASE_SHIFT 12 +#define DART_CNTL_U3_FLUSHTLB 0x400 +#define DART_CNTL_U3_ENABLE 0x200 +#define DART_CNTL_U3_SIZE_MASK 0x1ff +#define DART_CNTL_U3_SIZE_SHIFT 0 + +/* U4 registers */ +#define DART_BASE_U4_BASE_MASK 0xffffff +#define DART_BASE_U4_BASE_SHIFT 0 +#define DART_CNTL_U4_ENABLE 0x80000000 +#define DART_CNTL_U4_IONE 0x40000000 +#define DART_CNTL_U4_FLUSHTLB 0x20000000 +#define DART_CNTL_U4_IDLE 0x10000000 +#define DART_CNTL_U4_PAR_EN 0x08000000 +#define DART_CNTL_U4_IONE_MASK 0x07ffffff +#define DART_SIZE_U4_SIZE_MASK 0x1fff +#define DART_SIZE_U4_SIZE_SHIFT 0 + +#define DART_REG(r) (dart + ((r) >> 2)) +#define DART_IN(r) (in_be32(DART_REG(r))) +#define DART_OUT(r,v) (out_be32(DART_REG(r), (v))) + + +/* size of table in pages */ + + +/* DART table fields */ + +#define DARTMAP_VALID 0x80000000 +#define DARTMAP_RPNMASK 0x00ffffff + + +#define DART_PAGE_SHIFT 12 +#define DART_PAGE_SIZE (1 << DART_PAGE_SHIFT) + + +#endif /* _POWERPC_SYSDEV_DART_H */ -- cgit v1.3.1