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dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from PH0PR12MB7957.namprd12.prod.outlook.com (2603:10b6:510:281::22) by BY5PR12MB4243.namprd12.prod.outlook.com (2603:10b6:a03:20f::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.569.8; Thu, 29 Oct 2026 19:58:31 +0000 Received: from PH0PR12MB7957.namprd12.prod.outlook.com ([fe80::9251:acc2:cc63:3499]) by PH0PR12MB7957.namprd12.prod.outlook.com ([fe80::9251:acc2:cc63:3499%3]) with mapi id 15.21.0569.008; Thu, 29 Oct 2026 19:58:31 +0000 Date: Thu, 29 Oct 2026 21:58:21 +0200 From: Ido Schimmel To: Yingjie Wang Cc: "netdev@vger.kernel.org" , "dsahern@kernel.org" , "davem@davemloft.net" , "edumazet@kernel.org" , "kuba@kernel.org" , "pabeni@redhat.com" , "horms@kernel.org" , "herbert@gondor.apana.org.au" , "shuah@kernel.org" , "linux-kselftest@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH net 1/2] ipv4: devinet: update inheritance state only after parsed writes Message-ID: <20261029195821.GA1467575@shredder> References: <2b84b193384fd243fb70d9b0750cdcc9d695a158.1793283257.git.x-professor@outlook.com> Content-Type: text/plain; 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A rejected integer leaves the value > unchanged but sets its state bit, so a later update to conf/default skips > the device. > > Zero-length writes and writes ignored because their file position is > nonzero in strict sysctl mode have the same effect. proc_dointvec() > returns success for both without parsing a value. > > Use proc_dointvec_conv() with a converter that records successful integer > conversion. Update inheritance state and run post-set handling only after > both parsing and conversion succeed. The converter uses the same integer > helpers as proc_dointvec(), and valid same-value writes continue to mark a > setting as explicit. > > The issue was reproduced with ordinary sysctl writes in fresh network > namespaces, without kernel modification or error injection. On the base > kernel, lo/arp_ignore remained 0 after default/arp_ignore was set to 1 > following invalid, blank, zero-byte, or strict nonzero-offset writes. With > this change it inherited 1 in all four cases, while valid same-value and > changed-value writes retained 0 and 2. > > Fixes: 31be308541e9 ("[IPV4]: Add default config support after inetdev_init") > Signed-off-by: Yingjie Wang > --- > net/ipv4/devinet.c | 29 ++++++++++++++++++++++++++--- > 1 file changed, 26 insertions(+), 3 deletions(-) Why is this interesting? Who is even hitting this? Blamed commit is almost 20 years old.