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 56F89267B07; Fri, 1 May 2026 00:53:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777596788; cv=none; b=XIjmREvc5PLP9J2ORPeXKuPibElDKLEK1scy1K7koGue0D/dN4/7l+JtbuDPT5XrDIIGD7JkgLOGHDzxu3TCA6rAW6W0adNozqLGkFQ7s7Zdjn0z6an7LZtezbnQrPV+Zzh4dLyOJjUf3QUiIhLTg8M+Vy5kxezOVUS3GacftUQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777596788; c=relaxed/simple; bh=d0XT4/t91RskoEJQxzzKgFJMNLW9IouAU7J8aDIYAmw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=It2HLOkSCuL71ubSJ02ibBPLWro+z7KIYNBm1ZWDTPR8LzX+Ho81raU42+MDDqh6m7moptUz7qvPixSwf/beJgooZ8020alvuphNGounm7EmOS32iwDAXYBUnmOPWHLS5Mcigjvj8zqQyGhYpt0FBmWT0Abs4JLgE+XgO0egjB0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OvErAkrR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OvErAkrR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4F26C2BCB3; Fri, 1 May 2026 00:53:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777596787; bh=d0XT4/t91RskoEJQxzzKgFJMNLW9IouAU7J8aDIYAmw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OvErAkrReBqj9eyP4ir2aJOVzvOro/O1nq6Kgsz4yExaOJxK5Llu+zOelrVvOwbHN c7L3hx7EPsZ8NAYdqaJu2IzaNdf1diLw+GXrJGe2nQfrF9XqUTBsZiKcRx51Y5L8Ge r1DLtt67IZYqxTrX42O626oImVgWzpafNz0zfnCze2uRFaNcFZ8NKS6tHTKYyJ491T r4MZPaT+bkFpoT78G56dG7B0rdumxAzbCwFDAH9m8/s5H+9fTAcxuMyCWFU5kHjclR 75DHavrk4gF8/7PMyalAEHEcrZZRh8cwzDw7uv8jxfhQBjgQO8skWa99+jAcfJmaVj 8qQXNQapYWNVg== From: Sasha Levin To: stable@vger.kernel.org, Tung Nguyen Cc: Jakub Kicinski , Jon Maloy , "David S . Miller" , Robert Garcia , Al Viro , netdev@vger.kernel.org, tipc-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH 5.15.y] tipc: fix kernel warning when sending SYN message Date: Thu, 30 Apr 2026 20:53:05 -0400 Message-ID: <20260430160000.item003-5.15@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260429075033.234885-1-rob_garcia@163.com> References: <20260429075033.234885-1-rob_garcia@163.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Wed, Apr 29, 2026 at 03:50:33PM +0800, Robert Garcia wrote: > From: Tung Nguyen > > [ Upstream commit 11a4d6f67cf55883dc78e31c247d1903ed7feccc ] > > When sending a SYN message, this kernel stack trace is observed: [...] > It is because commit a41dad905e5a ("iov_iter: saner checks for attempt > to copy to/from iterator") has introduced sanity check for copying > from/to iov iterator. Lacking of copy direction from the iterator > viewpoint would lead to kernel stack trace like above. Thanks for the submission, but I don't think we need this in 5.15.y. The WARN this fix silences was added by a41dad905e5a ("iov_iter: saner checks for attempt to copy to/from iterator"), which landed in v6.1 and has never been backported to 5.15.y. Without that prerequisite the WARN isn't reachable in 5.15 — the SYN/ACK sends call copy_from_iter_full() with dsz=0 on a zero-initialized msghdr, and 5.15's _copy_from_iter() only WARNs for ITER_PIPE iters, not on data_source. Your ITER_SOURCE -> WRITE adaptation is correct, but since the bug is absent in 5.15 the patch isn't needed there. -- Thanks, Sasha