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/string.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 arch/powerpc/boot/string.h (limited to 'arch/powerpc/boot/string.h') diff --git a/arch/powerpc/boot/string.h b/arch/powerpc/boot/string.h new file mode 100644 index 000000000..2b28d1853 --- /dev/null +++ b/arch/powerpc/boot/string.h @@ -0,0 +1,21 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _PPC_BOOT_STRING_H_ +#define _PPC_BOOT_STRING_H_ +#include + +extern char *strcpy(char *dest, const char *src); +extern char *strcat(char *dest, const char *src); +extern char *strchr(const char *s, int c); +extern char *strrchr(const char *s, int c); +extern int strcmp(const char *s1, const char *s2); +extern int strncmp(const char *s1, const char *s2, size_t n); +extern size_t strlen(const char *s); +extern size_t strnlen(const char *s, size_t count); + +extern void *memset(void *s, int c, size_t n); +extern void *memmove(void *dest, const void *src, unsigned long n); +extern void *memcpy(void *dest, const void *src, unsigned long n); +extern void *memchr(const void *s, int c, size_t n); +extern int memcmp(const void *s1, const void *s2, size_t n); + +#endif /* _PPC_BOOT_STRING_H_ */ -- cgit v1.3.1