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/x86/boot/string.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 arch/x86/boot/string.h (limited to 'arch/x86/boot/string.h') diff --git a/arch/x86/boot/string.h b/arch/x86/boot/string.h new file mode 100644 index 000000000..4092bf2ed --- /dev/null +++ b/arch/x86/boot/string.h @@ -0,0 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef BOOT_STRING_H +#define BOOT_STRING_H + +/* Undef any of these macros coming from string_32.h. */ +#undef memcpy +#undef memset +#undef memcmp + +void *memcpy(void *dst, const void *src, size_t len); +void *memmove(void *dst, const void *src, size_t len); +void *memset(void *dst, int c, size_t len); +int memcmp(const void *s1, const void *s2, size_t len); +int bcmp(const void *s1, const void *s2, size_t len); + +/* Access builtin version by default. */ +#define memcpy(d,s,l) __builtin_memcpy(d,s,l) +#define memset(d,c,l) __builtin_memset(d,c,l) +#define memcmp __builtin_memcmp + +extern int strcmp(const char *str1, const char *str2); +extern int strncmp(const char *cs, const char *ct, size_t count); +extern size_t strlen(const char *s); +extern char *strstr(const char *s1, const char *s2); +extern char *strchr(const char *s, int c); +extern size_t strnlen(const char *s, size_t maxlen); +extern unsigned long long simple_strtoull(const char *cp, char **endp, + unsigned int base); +long simple_strtol(const char *cp, char **endp, unsigned int base); + +int boot_kstrtoul(const char *s, unsigned int base, unsigned long *res); +#endif /* BOOT_STRING_H */ -- cgit v1.3.1