Re: [PATCH bpf-next v1 09/10] bpf: disable and remove registers chain based liveness

[Eduard Zingerman <eddyz87@gmail.com>]

On Thu, 2025-09-11 at 22:19 +0800, kernel test robot wrote:
> Hi Eduard,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on bpf-next/master]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Eduard-Zingerman/bpf-bpf_verifier_state-cleaned-flag-instead-of-REG_LIVE_DONE/20250911-090604
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
> patch link:    https://lore.kernel.org/r/20250911010437.2779173-10-eddyz87%40gmail.com
> patch subject: [PATCH bpf-next v1 09/10] bpf: disable and remove registers chain based liveness
> config: x86_64-buildonly-randconfig-003-20250911 (https://download.01.org/0day-ci/archive/20250911/202509112112.wkWw6wJW-lkp@intel.com/config)
> compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250911/202509112112.wkWw6wJW-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202509112112.wkWw6wJW-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> > > kernel/bpf/verifier.c:19305:11: warning: variable 'err' is uninitialized when used here [-Wuninitialized]
>     19305 |                                 err = err ? : push_jmp_history(env, cur, 0, 0);
>           |                                       ^~~
>    kernel/bpf/verifier.c:19140:12: note: initialize the variable 'err' to silence this warning
>     19140 |         int n, err, states_cnt = 0;
>           |                   ^
>           |                    = 0
>    1 warning generated.
> 
> 
> vim +/err +19305 kernel/bpf/verifier.c

This was sloppy on my side, should look as follows:

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -19297,9 +19297,12 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
                         * the precision needs to be propagated back in
                         * the current state.
                         */
-                       if (is_jmp_point(env, env->insn_idx))
-                               err = err ? : push_jmp_history(env, cur, 0, 0);
-                       err = err ? : propagate_precision(env, &sl->state, cur, NULL);
+                       if (is_jmp_point(env, env->insn_idx)) {
+                               err = push_jmp_history(env, cur, 0, 0);
+                               if (err)
+                                       return err;
+                       }
+                       err = propagate_precision(env, &sl->state, cur, NULL);
                        if (err)
                                return err;
                        /* When processing iterator based loops above propagate_liveness and


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