From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.94 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793027224; b=L2E47/RMEtURQwDTDLwrHBSE9SuLfaqWZpPtnZWcv0pj0jtgftYUeFgte2/0xG82wTRJ HBcLDnlAp0WFNbCF472CP3tnTVTEX2EcXKvu3hjQGskZIOh7n9a/AgBtDwMH+H4j44kit 2OcLgdlwqlRfb18KxLu0O1a3gPYvjkSJaDBwxfq2fTApjvBmO0aGHxJEt1PoPnzuNsEDr jIADpIYi7XfPSY6yZMoXuCQaaxH6gHNtnXRvA6CTzTawwERjhHkWqkLyAXW4YF1HMrkUE 5DBWq6CQULc5SeFmCAPCW32ZisCR9wVyx4RGNeKAWgQdKTugTLuWZRkYCO3icnW6VQQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793027224; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=J0h2FhD1/ZqD4NmuBs6+MD7h5IX24/kXFYvf/GTy2DY=; b=iNgc1rwPE2QlQV93f7qDW+EzEQuhLT0O0OUH5ntKMeX4ebbmniucilX2ZztzDjKMZYCV oJl8R32C9oQt3E1zYorgGdjatYjo+prz3wGGtsD3QFOrVWLN7za8GDxEStxhFWVryVojV /nJ/LHaqwht7E/yook+ublZPwjrN5yH6TVqfplWcef+w/IhmS5kn8k0OJHiehnpkvbc9J ohgxihcigRv+eox0XRoxp5AnzeUxlJcIPMKHcduK+Nj4OetkRVLBTK8AOwSrCVDhjDd9f lgZy6CRIdTToI6zX42JiMdcJ9Y3UjnskSq+XhrQfjjVSIK4ywPbT8UaSiZWqbUfLzwQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=o1QiMdro; arc=none smtp.remote-ip=91.218.175.94 Received: from mta0.migadu.com (out-94.mta0.migadu.com [91.218.175.94]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC653606A31A for ; Mon, 26 Oct 2026 15:07:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org AC653606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=o1QiMdro X-Envelope-To: bpf@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=kiILAlyer4KDpB0b5u3nzcUamLQxdEs4r06HO3T5veo=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793027220; v=1; x=1793632020; b=o1QiMdroJ2Lo6pnEdfheer83seqjM1F3U78Hxrf7FV7j1Zcn6EKKSVGK25bI775ogEtCtwTJ 3yLxHD9UZ5KQrrI7S1xdsQR5fjqhyON+UdKS07BuqZpXpaEYDYCpm2KuoqZz3+wEW26+WpJ+tUD Cnm2+WWLxkkfPshCrQGll+Hg= X-Envelope-To: bpf@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 873537cec047169a; Mon, 26 Oct 2026 15:07:00 +0000 X-Mizu-Trace-ID: 873537cec047169a X-Migadu-Flow: FLOW_OUT Message-ID: Date: Mon, 26 Oct 2026 23:06:51 +0800 X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next v4 2/6] bpf: Add syscall common attrs support for xdp link_create To: Alexei Starovoitov , bpf@vger.kernel.org Cc: Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Shuah Khan , Kuniyuki Iwashima , Hangbin Liu , Martin Karsten , Masashi Honma , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20261024153608.58569-1-leon.hwang@linux.dev> <20261024153608.58569-3-leon.hwang@linux.dev> Content-Language: en-US From: Leon Hwang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2026/10/25 09:19, Alexei Starovoitov wrote: > On Sat, Oct 24, 2026 at 08:36 AM Leon Hwang wrote: >> Instead of passing bpf log or extack to bpf_xdp_link_attach(), pass an >> errmsg pointer to receive the kstrdup() error msg, because > > [...] > >> 2) passing extack will access underlying driver string out of dev_put() >> guard, which will crash kernel when the device is unloaded >> concurrently. > > Netlink does exactly that. > rtnl_setlink() looks up the dev with __dev_get_by_index(), so no refcnt, > do_setlink() -> dev_change_xdp_fd(dev, extack, ...) calls into the same > drivers that set the same strings, rtnl is unlocked, and only then > netlink_rcv_skb() -> netlink_ack() does strlen(extack->_msg). > All extack users work this way. kstrdup() in one of them fixes nothing. Oops, I was overthinking about it when self-reviewing the patch. Failed to verify the describing crash issue just now. I should verify my review when self-reviewing. > > Instead of patches 1 and 2: > Will change like this. > > I'm think I gave this suggestion earlier. Why did you go with strdup()? > Sorry for my overthinking. Will verify my review to my patches in the future. Thanks, Leon