From: Eder Zulian ezulian@redhat.com

commit 7f4ec77f3fee41dd6a41f03a40703889e6e8f7b2 upstream.

Initialize 'new_off' and 'pad_bits' to 0 and 'pad_type' to NULL in btf_dump_emit_bit_padding to prevent compiler warnings/errors which are observed when compiling with 'EXTRA_CFLAGS=-g -Og' options, but do not happen when compiling with current default options.

For example, when compiling libbpf with

$ make "EXTRA_CFLAGS=-g -Og" -C tools/lib/bpf/ clean all

Clang version 17.0.6 and GCC 13.3.1 fail to compile btf_dump.c due to following errors:

btf_dump.c: In function ‘btf_dump_emit_bit_padding’: btf_dump.c:903:42: error: ‘new_off’ may be used uninitialized [-Werror=maybe-uninitialized] 903 | if (new_off > cur_off && new_off <= next_off) { | ~~~~~~~~^~~~~~~~~~~ btf_dump.c:870:13: note: ‘new_off’ was declared here 870 | int new_off, pad_bits, bits, i; | ^~~~~~~ btf_dump.c:917:25: error: ‘pad_type’ may be used uninitialized [-Werror=maybe-uninitialized] 917 | btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 918 | in_bitfield ? new_off - cur_off : 0); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ btf_dump.c:871:21: note: ‘pad_type’ was declared here 871 | const char *pad_type; | ^~~~~~~~ btf_dump.c:930:20: error: ‘pad_bits’ may be used uninitialized [-Werror=maybe-uninitialized] 930 | if (bits == pad_bits) { | ^ btf_dump.c:870:22: note: ‘pad_bits’ was declared here 870 | int new_off, pad_bits, bits, i; | ^~~~~~~~ cc1: all warnings being treated as errors

Signed-off-by: Eder Zulian ezulian@redhat.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org Link: https://lore.kernel.org/bpf/20241022172329.3871958-3-ezulian@redhat.com Signed-off-by: He Zhe zhe.he@windriver.com Signed-off-by: Xiangyu Chen xiangyu.chen@windriver.com --- Build test passed. --- tools/lib/bpf/btf_dump.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index 0a7327541c17..46cce18c8308 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -867,8 +867,8 @@ static void btf_dump_emit_bit_padding(const struct btf_dump *d, } pads[] = { {"long", d->ptr_sz * 8}, {"int", 32}, {"short", 16}, {"char", 8} }; - int new_off, pad_bits, bits, i; - const char *pad_type; + int new_off = 0, pad_bits = 0, bits, i; + const char *pad_type = NULL;

if (cur_off >= next_off) return; /* no gap */