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-rw-r--r--include/linux/nospec.h4
-rw-r--r--kernel/bpf/core.c2
-rw-r--r--lib/usercopy.c7
3 files changed, 11 insertions, 2 deletions
diff --git a/include/linux/nospec.h b/include/linux/nospec.h
index c1e79f72cd89..9f0af4f116d9 100644
--- a/include/linux/nospec.h
+++ b/include/linux/nospec.h
@@ -11,6 +11,10 @@
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 ba3fff17e2f9..430c66d59ec7 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1910,9 +1910,7 @@ 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 1505a52f23a0..d29fe29c6849 100644
--- a/lib/usercopy.c
+++ b/lib/usercopy.c
@@ -3,6 +3,7 @@
#include <linux/fault-inject-usercopy.h>
#include <linux/instrumented.h>
#include <linux/uaccess.h>
+#include <linux/nospec.h>
/* out-of-line parts */
@@ -12,6 +13,12 @@ unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n
unsigned long res = n;
might_fault();
if (!should_fail_usercopy() && 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();
instrument_copy_from_user_before(to, from, n);
res = raw_copy_from_user(to, from, n);
instrument_copy_from_user_after(to, from, n, res);