From: Daniel Borkmann <daniel@iogearbox.net>
To: Andrii Nakryiko <andrii@kernel.org>, bpf@vger.kernel.org, ast@kernel.org
Cc: kernel-team@fb.com
Subject: Re: [PATCH bpf-next 03/13] libbpf: prevent UBSan from complaining about integer overflow
Date: Fri, 26 Nov 2021 00:19:31 +0100 [thread overview]
Message-ID: <8350db18-6e13-66da-220c-c1e53562326e@iogearbox.net> (raw)
In-Reply-To: <9e00239a-b44c-88d9-39b4-5e0ad7d49f3b@iogearbox.net>
On 11/25/21 11:21 PM, Daniel Borkmann wrote:
> On 11/24/21 1:23 AM, Andrii Nakryiko wrote:
>> Integer overflow is intentional, silence the sanitizer. It works
>> completely reliably on sane compilers and architectures.
>>
>> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
>> ---
>> tools/lib/bpf/btf.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
>> index 8024fe355ca8..be1dafd56a13 100644
>> --- a/tools/lib/bpf/btf.c
>> +++ b/tools/lib/bpf/btf.c
>> @@ -3127,6 +3127,7 @@ struct btf_dedup {
>> struct strset *strs_set;
>> };
>> +__attribute__((no_sanitize("signed-integer-overflow")))
>> static long hash_combine(long h, long value)
>> {
>> return h * 31 + value;
>>
>
> Sgtm, I guess my only question, was there a reason for not using e.g. __u64 in
> the first place? Meaning, __u64 hash_combine(__u64 h, __u64 value) plus the
> call-sites where you have h variable re-feeding into hash_combine().
Given the remainder of the series is all straight forward, I took that in already,
but would still be nice if we can silence the sanitizer complaint w/o such attribute
workaround.
Thanks,
Daniel
next prev parent reply other threads:[~2021-11-25 23:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-24 0:23 [PATCH bpf-next 00/13] Fix sanitizer-reported libbpf and selftest issues Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 01/13] tools/resolve_btf_ids: close ELF file on error Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 02/13] libbpf: fix potential misaligned memory access in btf_ext__new() Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 03/13] libbpf: prevent UBSan from complaining about integer overflow Andrii Nakryiko
2021-11-25 22:21 ` Daniel Borkmann
2021-11-25 23:19 ` Daniel Borkmann [this message]
2021-11-26 1:23 ` Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 04/13] libbpf: don't call libc APIs with NULL pointers Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 05/13] libbpf: fix glob_syms memory leak in bpf_linker Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 06/13] libbpf: fix using invalidated memory " Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 07/13] selftests/bpf: fix UBSan complaint about signed __int128 overflow Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 08/13] selftests/bpf: fix possible NULL passed to memcpy() with zero size Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 09/13] selftests/bpf: prevent misaligned memory access in get_stack_raw_tp test Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 10/13] selftests/bpf: fix misaligned memory access in queue_stack_map test Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 11/13] selftests/bpf: prevent out-of-bounds stack access in test_bpffs Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 12/13] selftests/bpf: fix misaligned memory accesses in xdp_bonding test Andrii Nakryiko
2021-11-24 0:23 ` [PATCH bpf-next 13/13] selftests/bpf: fix misaligned accesses in xdp and xdp_bpf2bpf tests Andrii Nakryiko
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