1. Feb 24, 2020
    • Kees Cook's avatar
      n_tty: Distribute switch variables for initialization · e24cd4e6
      Kees Cook authored
      Variables declared in a switch statement before any case statements
      cannot be automatically initialized with compiler instrumentation (as
      they are not part of any execution flow). With GCC's proposed automatic
      stack variable initialization feature, this triggers a warning (and they
      don't get initialized). Clang's automatic stack variable initialization
      (via CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also
      doesn't initialize such variables[1]. Note that these warnings (or silent
      skipping) happen before the dead-store elimination optimization phase,
      so even when the automatic initializations are later elided in favor of
      direct initializations, the warnings remain.
      
      To avoid these problems, move such variables into the "case" where
      they're used or lift them up into the main function body.
      
      drivers/tty/n_tty.c: In function ‘__process_echoes’:
      drivers/tty/n_tty.c:657:18: warning: statement will never be executed [-Wswitch-unreachable]
        657 |     unsigned int num_chars, num_bs;
            |                  ^~~~~~~~~
      
      [1] https://bugs.llvm.org/show_bug.cgi?id=44916
      
      
      
      Reviewed-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Link: https://lore.kernel.org/r/20200220062313.69209-1-keescook@chromium.org
      
      
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e24cd4e6
  2. Feb 21, 2020
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