From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) (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 A06FF433049; Tue, 25 Aug 2026 12:55:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787662529; cv=none; b=hQhv+LwBm12sW86pEtm/3IUHvl9CDlz8jarbr5pME/NtnGHkBKBNH5d1D0zliuFtIR7dR/fCv/2gbmFAFaSkFXjhYsbN7zrXPzynY7fpj6i+cULyt4yZgmCN4B4SNassm8RsY5P7a+vNkkFRZvJ8TOGoYHfUxJwsH08XA4/kyLI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787662529; c=relaxed/simple; bh=lMbadGI6bG/xSqPmC06/CiaQldQw2eevZZ2Iw3Z1O70=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=JeZBEjb3yvXqQojy+2qPUKyLOOhZupevCQ8gijb9K7wXAuFGBOCm25OFYvnpmMRz9mdxzlIe2HeFMBor6xP/VZS/nJ5keH/w987ESY5Vgi4jw6x82SE/y418vW7RjnhTLAH7JchVZ/OvddRZynH5V2QA8wF8ezGQqEO3iE6V+fM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b=bRUw33u6; arc=none smtp.client-ip=216.40.44.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b="bRUw33u6" Received: from omf20.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 28AE41C1959; Tue, 25 Aug 2026 12:55:26 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf20.hostedemail.com (Postfix) with ESMTPA id 6991F20026; Tue, 25 Aug 2026 12:55:24 +0000 (UTC) Date: Tue, 25 Aug 2026 08:56:07 -0400 From: Steven Rostedt To: Haotian Zhang Cc: mhiramat@kernel.org, mark.rutland@arm.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify Message-ID: <20260825085607.46c3814e@gandalf.local.home> In-Reply-To: <20260825093421.7377-1-vulab@iscas.ac.cn> References: <20260825093421.7377-1-vulab@iscas.ac.cn> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: menmnxybipu397wij5ewrq3ej44uj9op X-Rspamd-Server: rspamout06 X-Rspamd-Queue-Id: 6991F20026 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18PrpqXjqvKvNRYVyAs7J+unq72YZfMGfw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=OKKP5tcxu1fq6t62908DksMjio6J6HxeeQ7e0FapnVc=; b=bRUw33u6AYtRa3uD+i/+6oUxPbsMW0RwCQw8Vnt4vertCAhdVtRhuFbUVEctlCU6biqnyknGolN4hqifgIK5FLbiMt5d/ECoKaSPHQFKDgQeET/RGi8atusBdoeSuxuHiPHdtiNlcPhWSFI6o6hIe6NEYVemPC/JzNsVUxEKDcY= X-HE-Tag: 1787662524-38958 X-HE-Meta: U2FsdGVkX1/goqlqKWlZLlja3EGV0C6PmBqz/4pYOEh/ZCgot1fGN0qkIW4CxVc2zyGutnBp/vs7fxX+ns5VSTP21/OnIvYmQHYVs29DjQ2oUH9PCBjazs+2wYXaInB03Ic9nZm0Smx9OM51dM3A7YyvV2+52+g7afiJztYoOLtmh1MeBOLc+XOCzpzCZhfHKlH08OpayRgGG3kvlxMDHRKjONZSVhhJvj+USmK3t6eNtEgGjA1MU3D7hrdZ2qEXjzye6+U3hCxDTcX3DFPF9h6tmlKcIb7vmE3ekWKrqyp955snIlK+63p/xTr8YN/F On Tue, 25 Aug 2026 17:34:21 +0800 Haotian Zhang wrote: > ftrace_direct_multi_init() assigns kthread_run()'s return value to > simple_tsk without an IS_ERR() check. When kthread_run() fails it > returns ERR_PTR(-ENOMEM), but init still returns 0, so the module loads > with simple_tsk holding an error pointer. On unload, > ftrace_direct_multi_exit() then passes that ERR_PTR to kthread_stop(), > leading to a null-pointer-dereference. > > Check the return value of kthread_run() with IS_ERR(); on failure, > unregister the ftrace direct call and propagate the error code. > > Fixes: e1067a07cfbc ("ftrace/samples: Add module to test multi direct modify interface") > Signed-off-by: Haotian Zhang > --- > samples/ftrace/ftrace-direct-multi-modify.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c > index 8f7986d698d8..f339131654c7 100644 > --- a/samples/ftrace/ftrace-direct-multi-modify.c > +++ b/samples/ftrace/ftrace-direct-multi-modify.c > @@ -364,8 +364,13 @@ static int __init ftrace_direct_multi_init(void) > > ret = register_ftrace_direct(&direct, my_tramp); > > - if (!ret) > + if (!ret) { > simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); > + if (IS_ERR(simple_tsk)) { > + unregister_ftrace_direct(&direct, my_tramp, true); > + ret = PTR_ERR(simple_tsk); > + } > + } > return ret; > } > And simplify this one too. Oh, and if you have a series "[PATCH 1/2]" then you need a cover letter and have each patch be a reply to of that patch. Otherwise just send the patches as is without the numbered series. Because sending the patches one by one with a series number makes it confusing. -- Steve -- Steve