From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-176.mta1.migadu.com (out-176.mta1.migadu.com [95.215.58.176]) (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 2AF4730D3E5 for ; Thu, 18 Jun 2026 04:09:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781755761; cv=none; b=UH5iFskyFwooWUf7Q1CIq7GusaenNETYbkrWr+F3Jk4WMei05WSGqQZzGhot3+EfL55PSOvo5Tvnrr8qjI5LI8JU6uUxMqczM/XWdLg+z7/vCgX9dVjPB47RdiwT2pqPZIiFinVjIIDL/Cziz4GYB5W1IeD71AIkGin1UORlqiM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781755761; c=relaxed/simple; bh=dh5wCK0lHCrCxrrHLiVzXvxBW2zSxafnp2sTztekImI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PJqt+xXi+pC/QWrKa7DwyCLMzzP7sw3836EMCL2fyhkgFqdy93zmMGahxjv85Dj5vFNSKlOOUarVYRzEsBkCwM4uAWnS2G6ZCojPSeulkDb/9P1AZf0zbS0HAm33XdtkzTH2nzcKlUAm+gqqOZTNC/RlWto1Xi1sZ6rzPuhGlGQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=lUtFJCZm; arc=none smtp.client-ip=95.215.58.176 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) header.d=linux.dev header.i=@linux.dev header.b="lUtFJCZm" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1781755748; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wRNtQtrmBi3UmEh4UWSO7FkcYQWctEZwQil6uxg8zgc=; b=lUtFJCZmCZIl2AfZL4/j39wxxE1OV10WNoWd8u0jUDD1ywF+p1BcuO8tB4dqJ6AW4BO6e2 eRtPeZJLUVSeQqxYUsl3fRm9sduJ4wM1q9a7XLyGuP8FR3G8SS+y2v18nh46BMU+mJqH4D Dq92jktXbnAkSAIftxFGlIMiwN+iaZE= Date: Thu, 18 Jun 2026 12:08:53 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH net] ipv6: ndisc: fix NULL deref in accept_untracked_na() To: Weiming Shi , "David S . Miller" , David Ahern , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Xiang Mei References: <20260617065512.2529757-2-bestswngs@gmail.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Jiayuan Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 6/17/26 9:38 PM, Weiming Shi wrote: > On Wed Jun 17, 2026 at 4:32 PM CST, Jiayuan Chen wrote: >> On 6/17/26 2:55 PM, Weiming Shi wrote: >>> accept_untracked_na() re-fetches the inet6_dev with __in6_dev_get(dev) >>> and dereferences idev->cnf.accept_untracked_na without a NULL check, >> >> Does ipv6_rpl_srh_rcv have same problem? > Hi, > > Yes, ipv6_rpl_srh_rcv() has the same missing check. It reads > idev->cnf.rpl_seg_enabled right after __in6_dev_get(skb->dev) with no > NULL check, while seg6 and ioam6 in the same file both check it. > > But I tried to trigger it and couldn't. With a guard added as an instrument, > idev never came back NULL over tens of millions of RPL packets while > flapping the MTU, so I can't say it's actually reachable. Can you need to add mdelay to enlarge the race window to reproduce it? I believe we need more precise traffic and timing control, instead of aggressively ramping up traffic and load in an attempt to reproduce the issue.