From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 374474A32; Thu, 6 Aug 2026 13:41:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786023691; cv=none; b=Vku1R8af4lBGm1MqG3L7rqATeJz4Kw2rK7VzrzP2Wsby740XMi/q/1dP/5SxtXQW+PLX+9+gcAgsUikEdvBwtHeOvxCkc0ELh1QvyyNCuzniQhfiihoC6foD2OaVkOMZNPvkHIA7/DIRUZdxAwfv4h7Ts+2VTM9rC1BqyqCwlz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786023691; c=relaxed/simple; bh=vKwmvMQ3K/xckpG0mZgEBf79C8grhiemZP7bBkbDmLA=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=nmdk8m5uYHL+rJP8pevWYq8vlB55tyZMQbyfjQv2yJlMi6A5T1jU4XtTOlA2HUjsuuCngxnQNCSgEzocTn76RlLRxsjZ1rE6Z3yoKAARCJfwNKcmOC4IpudIWnz/vWRsiT5941FXvmJ6tHdc+kSj05UexKx3Gevw9VcEHHPkMfU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GqPqoInk; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GqPqoInk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 192F11F000E9; Thu, 6 Aug 2026 13:41:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786023689; bh=Ru6IPOsdzDitRU6k/P9dLvDIcUp6eZjujRM3axRZpGI=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=GqPqoInklXR36s3aFWIeh8vu0mUyTXHZ20MxRidbesHpWU2j+OkJQHHtBfP81A8DE IvMwh9nHvRv7CPN4NDkfKXDeDulcrob2V8PS2ICtBuqfq0K/tPlwuKRiV9wXtiWP6c RwCEQaxIkVX3/jo4I2u6Q6A1Ivm231BBnQyon6DyRtKj0ShFTIc61f3doUYgjpkPR/ 6QDu+Di/RbRZSEQ0J3YnpIqXaikj6VMrCYXsJTDLyO+dalKkkmvcs9LIgpBXPzQsRK nd3+nuoI7TSCc+D9bJ2iRR5xfk18/AvKTKOU0qCkKsQ7iODApKVbjhdb+X4Wc+BXVi b/TUVxTP//Qkg== Date: Thu, 6 Aug 2026 22:41:25 +0900 From: Masami Hiramatsu (Google) To: Luigi Rizzo Cc: Naveen N Rao , Luigi Rizzo , "David S . Miller" , JP Kobryn , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kprobes: Fix NULL pointer dereference in unregister_kretprobes() Message-Id: <20260806224125.6c1048fed96cac11bfb31233@kernel.org> In-Reply-To: References: <20260805161221.2428623-1-lrizzo@google.com> <20260806090235.e40c75f84f8a01b9a80fd570@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@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 Thu, 6 Aug 2026 09:23:29 +0200 Luigi Rizzo wrote: > On Thu, Aug 6, 2026 at 2:02 AM Masami Hiramatsu wrote: > > > > On Wed, 5 Aug 2026 16:12:21 +0000 > > Luigi Rizzo wrote: > > > > > In unregister_kretprobes(), rps[i]->rph can be NULL e.g. when called > > > after kretprobe failed registration. Under !CONFIG_KRETPROBE_ON_RETHOOK, > > > the unconditional access to rps[i]->rph->rp, causes a kernel panic due > > > to NULL pointer dereference. > > > > This is not a bug, since if register_kretprobe(rp) fails, rp must NOT be > > passed to unregister_kretprobe(rp). Or, do you find any cases where > > register_kretprobe() fails, preventing proper cleanup, and requiring > > unregister_kretprobe()? If so, we have to fix that case. > > Masami, you are right, the kernel tree does not call unregister_kretprobes() > on a failed registration. I was confused by the unregister_kretprobes(rps, i); > call in the cleanup in register_kretprobes(), but the failed entry i is > not unregistered). Yes, in that case rps[i] is not unregistered ;) > > So aside from protective coding (but where would one stop ? > null rps, null rps[i], ... ), there is no need for this patch. OK, Thanks for the confirmation! Thanks, > > thanks for the feedback > Luigi -- Masami Hiramatsu (Google)