diff options
| -rw-r--r-- | include/linux/nospec.h | 4 | ||||
| -rw-r--r-- | kernel/bpf/core.c | 2 | ||||
| -rw-r--r-- | lib/usercopy.c | 7 |
3 files changed, 11 insertions, 2 deletions
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 cbbd0168f50c..067d504d2841 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1373,9 +1373,7 @@ 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 3744b2a8e591..1e99c1baf4ff 100644 --- a/lib/usercopy.c +++ b/lib/usercopy.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include <linux/uaccess.h> +#include <linux/nospec.h> /* out-of-line parts */ @@ -9,6 +10,12 @@ unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n unsigned long res = n; might_fault(); if (likely(access_ok(VERIFY_READ, 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); } |