netdev - Re: [PATCH bpf] selftests/bpf: fix segfault of test

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Date:   Tue, 12 Mar 2019 22:01:10 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Yonghong Song <yhs@...com>, netdev@...r.kernel.org
Cc:     Alexei Starovoitov <ast@...com>, kernel-team@...com
Subject: Re: [PATCH bpf] selftests/bpf: fix segfault of test_progs when prog
 loading failed

On 03/12/2019 06:21 AM, Yonghong Song wrote:
> The test_progs subtests, test_spin_lock() and test_map_lock(),
> requires BTF present to run successfully.
> Currently, when BTF failed to load, test_progs will segfault,
>   $ ./test_progs
>   ...
>   12: (bf) r1 = r8
>   13: (85) call bpf_spin_lock#93
>   map 'hash_map' has to have BTF in order to use bpf_spin_lock
> 
>   libbpf: -- END LOG --
>   libbpf: failed to load program 'map_lock_demo'
>   libbpf: failed to load object './test_map_lock.o'
>   test_map_lock:bpf_prog_load errno 13
>   Segmentation fault
> 
> The segfault is caused by uninitialized variable "obj", which
> is used in bpf_object__close(obj), when bpf prog failed to load.
> 
> Initializing variable "obj" to NULL in two occasions fixed the problem.
>   $ ./test_progs
>   ...
>   Summary: 219 PASSED, 2 FAILED
> 
> Fixes: b4d4556c3266 ("selftests/bpf: add bpf_spin_lock verifier tests")
> Fixes: ba72a7b4badb ("selftests/bpf: test for BPF_F_LOCK")
> Reported-by: Daniel Borkmann <daniel@...earbox.net>
> Signed-off-by: Yonghong Song <yhs@...com>

Applied, thanks!