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/vdso/limits.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 include/vdso/limits.h (limited to 'include/vdso/limits.h') diff --git a/include/vdso/limits.h b/include/vdso/limits.h new file mode 100644 index 000000000..0197888ad --- /dev/null +++ b/include/vdso/limits.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __VDSO_LIMITS_H +#define __VDSO_LIMITS_H + +#define USHRT_MAX ((unsigned short)~0U) +#define SHRT_MAX ((short)(USHRT_MAX >> 1)) +#define SHRT_MIN ((short)(-SHRT_MAX - 1)) +#define INT_MAX ((int)(~0U >> 1)) +#define INT_MIN (-INT_MAX - 1) +#define UINT_MAX (~0U) +#define LONG_MAX ((long)(~0UL >> 1)) +#define LONG_MIN (-LONG_MAX - 1) +#define ULONG_MAX (~0UL) +#define LLONG_MAX ((long long)(~0ULL >> 1)) +#define LLONG_MIN (-LLONG_MAX - 1) +#define ULLONG_MAX (~0ULL) +#define UINTPTR_MAX ULONG_MAX + +#endif /* __VDSO_LIMITS_H */ -- cgit v1.3.1