Re: [PATCH v12 bpf-next 7/8] selftests/bpf: test kind encoding/decoding

> diff --git a/tools/testing/selftests/bpf/prog_tests/btf_kind.c b/tools/testing/selftests/bpf/prog_tests/btf_kind.c
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/btf_kind.c

[ ... ]

> +static void write_raw_btf(const char *btf_path, void *raw_btf, size_t raw_size)
> +{
> +	int fd = open(btf_path, O_WRONLY | O_CREAT);
                                          ^^^^^^^^

Should this include a mode argument?  When O_CREAT is specified,
open() requires a third mode_t parameter.  Without it, the file
permissions are determined by whatever value happens to be on the
stack, since open() is variadic.

Something like this would avoid the undefined behavior:

    int fd = open(btf_path, O_WRONLY | O_CREAT | O_TRUNC, 0600);

> +
> +	write(fd, raw_btf, raw_size);
> +	close(fd);
> +}

[ ... ]


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/22637324186