seccomp: Replace smp_read_barrier_depends() with lockless_dereference()

Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the change.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 4f44028943e663391fe35827c8c5acb4966b5101..980fd26da22e05a1a0ab741f1c72ac3c23aeba87 100644 (file)
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -175,17 +175,16 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
  */
 static u32 seccomp_run_filters(struct seccomp_data *sd)
 {
-       struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
        struct seccomp_data sd_local;
        u32 ret = SECCOMP_RET_ALLOW;
+       /* Make sure cross-thread synced filter points somewhere sane. */
+       struct seccomp_filter *f =
+                       lockless_dereference(current->seccomp.filter);
 
        /* Ensure unexpected behavior doesn't result in failing open. */
        if (unlikely(WARN_ON(f == NULL)))
                return SECCOMP_RET_KILL;
 
-       /* Make sure cross-thread synced filter points somewhere sane. */
-       smp_read_barrier_depends();
-
        if (!sd) {
                populate_seccomp_data(&sd_local);
                sd = &sd_local;