diff --git a/include/linux/nospec.h b/include/linux/nospec.h index 0c5ef54fd416..207ef2a20e48 100644 --- a/include/linux/nospec.h +++ b/include/linux/nospec.h @@ -9,6 +9,10 @@ struct task_struct; +#ifndef barrier_nospec +# define barrier_nospec() do { } while (0) +#endif + /** * array_index_mask_nospec() - generate a ~0 mask when index < size, 0 otherwise * @index: array element index diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 6b33a8a148b8..556d67afc493 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1567,9 +1567,7 @@ out: * reuse preexisting logic from Spectre v1 mitigation that * happens to produce the required code on x86 for v4 as well. */ -#ifdef CONFIG_X86 barrier_nospec(); -#endif CONT; #define LDST(SIZEOP, SIZE) \ STX_MEM_##SIZEOP: \ diff --git a/lib/usercopy.c b/lib/usercopy.c index cbb4d9ec00f2..82881e0bcaa1 100644 --- a/lib/usercopy.c +++ b/lib/usercopy.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include #include +#include /* out-of-line parts */ @@ -10,6 +11,12 @@ unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n unsigned long res = n; might_fault(); if (likely(access_ok(from, n))) { + /* + * Ensure that bad access_ok() speculation will not + * lead to nasty side effects *after* the copy is + * finished: + */ + barrier_nospec(); kasan_check_write(to, n); res = raw_copy_from_user(to, from, n); }