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/boot/stdlib.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 arch/powerpc/boot/stdlib.c (limited to 'arch/powerpc/boot/stdlib.c') diff --git a/arch/powerpc/boot/stdlib.c b/arch/powerpc/boot/stdlib.c new file mode 100644 index 000000000..868b019d6 --- /dev/null +++ b/arch/powerpc/boot/stdlib.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * stdlib functions + * + * Author: Scott Wood + * + * Copyright (c) 2007 Freescale Semiconductor, Inc. + */ + +#include "stdlib.h" + +/* Not currently supported: leading whitespace, sign, 0x prefix, zero base */ +unsigned long long int strtoull(const char *ptr, char **end, int base) +{ + unsigned long long ret = 0; + + if (base > 36) + goto out; + + while (*ptr) { + int digit; + + if (*ptr >= '0' && *ptr <= '9' && *ptr < '0' + base) + digit = *ptr - '0'; + else if (*ptr >= 'A' && *ptr < 'A' + base - 10) + digit = *ptr - 'A' + 10; + else if (*ptr >= 'a' && *ptr < 'a' + base - 10) + digit = *ptr - 'a' + 10; + else + break; + + ret *= base; + ret += digit; + ptr++; + } + +out: + if (end) + *end = (char *)ptr; + + return ret; +} -- cgit v1.3.1