1 files changed, 17 insertions, 4 deletions

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 54a0347ca812..a635ecba6fe2 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -149,7 +149,7 @@ static void populate_seccomp_data(struct seccomp_data *sd)
 
         sd->nr = syscall_get_nr(task, regs);
         sd->arch = syscall_get_arch();
-        syscall_get_arguments(task, regs, 0, 6, args);
+        syscall_get_arguments(task, regs, args);
         sd->args[0] = args[0];
         sd->args[1] = args[1];
         sd->args[2] = args[2];
@@ -331,7 +331,7 @@ static int is_ancestor(struct seccomp_filter *parent,
  * Expects sighand and cred_guard_mutex locks to be held.
  *
  * Returns 0 on success, -ve on error, or the pid of a thread which was
- * either not in the correct seccomp mode or it did not have an ancestral
+ * either not in the correct seccomp mode or did not have an ancestral
  * seccomp filter.
  */
 static inline pid_t seccomp_can_sync_threads(void)
@@ -502,7 +502,10 @@ out:
  *
  * Caller must be holding current->sighand->siglock lock.
  *
- * Returns 0 on success, -ve on error.
+ * Returns 0 on success, -ve on error, or
+ *   - in TSYNC mode: the pid of a thread which was either not in the correct
+ *     seccomp mode or did not have an ancestral seccomp filter
+ *   - in NEW_LISTENER mode: the fd of the new listener
  */
 static long seccomp_attach_filter(unsigned int flags,
                                   struct seccomp_filter *filter)
@@ -1258,6 +1261,16 @@ static long seccomp_set_mode_filter(unsigned int flags,
         if (flags & ~SECCOMP_FILTER_FLAG_MASK)
                 return -EINVAL;
 
+        /*
+         * In the successful case, NEW_LISTENER returns the new listener fd.
+         * But in the failure case, TSYNC returns the thread that died. If you
+         * combine these two flags, there's no way to tell whether something
+         * succeeded or failed. So, let's disallow this combination.
+         */
+        if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
+            (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER))
+                return -EINVAL;
+
         /* Prepare the new filter before holding any locks. */
         prepared = seccomp_prepare_user_filter(filter);
         if (IS_ERR(prepared))
@@ -1304,7 +1317,7 @@ out:
                 mutex_unlock(&current->signal->cred_guard_mutex);
 out_put_fd:
         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
-                if (ret < 0) {
+                if (ret) {
                         listener_f->private_data = NULL;
                         fput(listener_f);
                         put_unused_fd(listener);