Re: [U-Boot] [PATCH 2/2] libavb: Fix build warnings after updating the lib

Hi Sam,

CC: LIBAVB people (w.r.t. libavb fixes in U-Boot)

I can reproduce the compiler warnings myself and I confirm they are fixed with this patch. More comments below.

On Thu, Aug 15, 2019 at 11:04:03PM +0300, Sam Protsenko wrote:

After updating libavb to most recent version from AOSP/master, two new warnings appear:

Warning #1:

lib/libavb/avb_cmdline.c: In function 'avb_append_options':
lib/libavb/avb_cmdline.c:365:15: warning: 'dm_verity_mode' may be
                                 used uninitialized in this function
                                 [-Wmaybe-uninitialized]
     new_ret = avb_replace(
               ^~~~~~~~~~~~
         slot_data->cmdline, "$(ANDROID_VERITY_MODE)", dm_verity_mode);
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lib/libavb/avb_cmdline.c:374:8: warning: 'verity_mode' may be used
                                uninitialized in this function
                                [-Wmaybe-uninitialized]
   if (!cmdline_append_option(
        ^~~~~~~~~~~~~~~~~~~~~~
           slot_data, "androidboot.veritymode", verity_mode)) {
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Warning #2:

lib/libavb/avb_slot_verify.c: In function 'avb_slot_verify':
lib/libavb/avb_slot_verify.c:1349:23: warning: 'ret' may be used
                                      uninitialized in this function
                                      [-Wmaybe-uninitialized]
   AvbSlotVerifyResult ret;
                       ^~~

FWIW, few of Linux commits do word-wrapping of ASCII/console dumps for the sake of improved readability and git grepping. Recent checkpatch versions don't warn on that.

Fix those by providing default return values to affected functions.

Signed-off-by: Sam Protsenko semen.protsenko@linaro.org

lib/libavb/avb_cmdline.c | 3 ++- lib/libavb/avb_slot_verify.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/libavb/avb_cmdline.c b/lib/libavb/avb_cmdline.c index cb5b98e423..684c512bb9 100644 --- a/lib/libavb/avb_cmdline.c +++ b/lib/libavb/avb_cmdline.c @@ -357,7 +357,8 @@ AvbSlotVerifyResult avb_append_options( // Should never get here because MANAGED_RESTART_AND_EIO is // remapped by avb_manage_hashtree_error_mode(). avb_assert_not_reached();

•    break;
  

•    ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT;
  

•    goto out;
  

With AVB_ENABLE_DEBUG enabled, PVS-Studio reports: lib/libavb/avb_cmdline.c 360 warn V779 Unreachable code detected. It is possible that an error is present.

How about replacing the 'break' statement with a 'fallthrough' comment? It shuts down the warning w/o changing the functionality.

   default:
     ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT;
     goto out;

diff --git a/lib/libavb/avb_slot_verify.c b/lib/libavb/avb_slot_verify.c index 5d400b38aa..c0defdf9c9 100644 --- a/lib/libavb/avb_slot_verify.c +++ b/lib/libavb/avb_slot_verify.c @@ -1346,7 +1346,7 @@ AvbSlotVerifyResult avb_slot_verify(AvbOps* ops, AvbSlotVerifyFlags flags, AvbHashtreeErrorMode hashtree_error_mode, AvbSlotVerifyData** out_data) {

• AvbSlotVerifyResult ret;

• AvbSlotVerifyResult ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT;

What should we do with these out-of-tree libavb fixes? IMHO they are not specific to U-Boot and should be upstream-able. IMHO it is not healthy to accumulate too many of them, since this will make future libavb sync more painful.