From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5DBCD16416; Mon, 27 Nov 2023 12:29:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="faBhkNcZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C7A0C433C7; Mon, 27 Nov 2023 12:29:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701088192; bh=PiZRO1SG/+v1197piJzNlutqwuYFIV33BwcNtwlceR0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=faBhkNcZ6Lg/lPlwJkGVkf3gt1DsbP3fiUtDbFqMmIyD2CIwYudF9I0yiGyWoAMPv TjAYJcfSgZRj/d0qxaQHXWaNM57CBqaJ1XYTvzWx3mazA38R3CdI2wPqbrpHZxFRE7 Azdz6Po2DlfhUxh+Rps/mC/ZpCgmG6iXTnkTXiUApJc4Pmbpq+7ztNhBt1PMuY9VTy smsJmhIq3gttUpuc0LXpq4ctPcgTWysTNZ52hI9zK8qaJdTIFD5Jm/D4D5/wEU9s3D SD8ohFDDCw4jv8xTjusc8v/a6AoOvDI+K2P7Keq0B10Zyium49wr6Ym+JPKe4tiGCQ u3sC8dSwwrEmQ== Message-ID: <7418fa0c-c0c2-4615-ba55-f148ceb82328@kernel.org> Date: Mon, 27 Nov 2023 13:29:46 +0100 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net 4/4] selftests/net: mptcp: fix uninitialized variable warnings Content-Language: en-GB, fr-BE To: Willem de Bruijn , netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, edumazet@google.com, pabeni@redhat.com, linux-kselftest@vger.kernel.org, Willem de Bruijn , Florian Westphal , MPTCP Upstream References: <20231124171645.1011043-1-willemdebruijn.kernel@gmail.com> <20231124171645.1011043-5-willemdebruijn.kernel@gmail.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== In-Reply-To: <20231124171645.1011043-5-willemdebruijn.kernel@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Willem, (+ cc MPTCP list) On 24/11/2023 18:15, Willem de Bruijn wrote: > From: Willem de Bruijn > > Same init_rng() in both tests. The function reads /dev/urandom to > initialize srand(). In case of failure, it falls back onto the > entropy in the uninitialized variable. Not sure if this is on purpose. > But failure reading urandom should be rare, so just fail hard. While > at it, convert to getrandom(). Which man 4 random suggests is simpler > and more robust. > > mptcp_inq.c:525:6: > mptcp_connect.c:1131:6: > > error: variable 'foo' is used uninitialized > whenever 'if' condition is false > [-Werror,-Wsometimes-uninitialized] Thank you for the patch! It looks good to me: Reviewed-by: Matthieu Baerts > Fixes: 048d19d444be ("mptcp: add basic kselftest for mptcp") > Fixes: b51880568f20 ("selftests: mptcp: add inq test case") > Cc: Florian Westphal > Signed-off-by: Willem de Bruijn > > ---- > > When input is randomized because this is expected to meaningfully > explore edge cases, should we also add > 1. logging the random seed to stdout and > 2. adding a command line argument to replay from a specific seed > I can do this in net-next, if authors find it useful in this case. I think we should have done that from the beginning, otherwise we cannot easily reproduce these edge cases. To be honest, I don't think this technique helped to find bugs, and it was probably used here as a good habit to increase the coverage. But on the other hand, we might not realise some inputs are randomised and can cause instabilities in the tests because we don't print anything about that. So I would say that the minimal thing to do is to log the random seed. But it might not be that easy to do, for example 'mptcp_connect' is used a lot of time by the .sh scripts: printing this seed number each time 'mptcp_connect' is started will "flood" the logs. Maybe we should only print that at the end, in case of errors: e.g. in xerror() and die_perror() for example, but I see 'exit(1)' is directly used in other places... That's more code to change, but if it is still OK for you to do that, please also note that you will need to log this to stderr: mptcp_connect prints what has been received from the other peer to stdout. Because it is more than just adding a 'printf()', I just created a ticket in our bug tracker, so anybody can look at that and check all the details about that: https://github.com/multipath-tcp/mptcp_net-next/issues/462 > --- > tools/testing/selftests/net/mptcp/mptcp_connect.c | 11 ++++------- > tools/testing/selftests/net/mptcp/mptcp_inq.c | 11 ++++------- > 2 files changed, 8 insertions(+), 14 deletions(-) > > diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c > index c7f9ebeebc2c5..d2043ec3bf6d6 100644 > --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c > +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c (...) > @@ -1125,15 +1126,11 @@ int main_loop_s(int listensock) > > static void init_rng(void) > { > - int fd = open("/dev/urandom", O_RDONLY); > unsigned int foo; > > - if (fd > 0) { I just realised that here, we could have fd == 0 which is a valid value. I don't think we would have that when executing the selftests, but that's another reason to change this :) > - int ret = read(fd, &foo, sizeof(foo)); > - > - if (ret < 0) > - srand(fd + foo); > - close(fd); > + if (getrandom(&foo, sizeof(foo), 0) == -1) { > + perror("getrandom"); > + exit(1); > } > > srand(foo); Cheers, Matt