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 CFF12483BDE for ; Thu, 27 Aug 2026 15:09:24 +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=1787843366; cv=none; b=Xoq1PzAR7Xrww7T40Z0DP2ow+MHd+dN6aU2NS9FRRXKRnHQ/2okSP5+4fkx2KPqIyoxzsI2zDsCOeuCc+LS8mxx4W74Diw/4qA5DvLF4rmnEUNNRTOKrg+9Dhp+PxxBPscfvquoQaia5/CURnJqXszdw7VfRG1k8IZm3p0oKXws= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787843366; c=relaxed/simple; bh=THvfUMg5TbfzBxeyN4QirCFqOs9S7SFIChRddP64VeM=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=dTIcRFjJv89ZKJ4r2/BPbw7uwQGcKL6zdsODhFTWPOD0QADvybGVPtoS7nnEfeLywfWfrFcJ+osU6g8eH3DYGcvXRyjzrj2eEwKIzXHpMybKkS/moL8BVMEo6KjV0sRO9Kaw+WVX8nhqpk4bOBtuxTVcmJIRqfCwxGQZrG1hqLM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=l3Xc6vnv; 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="l3Xc6vnv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6DC41F00ACA; Thu, 27 Aug 2026 15:09:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787843363; bh=OoOb25/cKzKtyIcy2W/62Wt5IvtdO4qR8/ih5HeWboY=; h=Date:From:To:Cc:Subject:References; b=l3Xc6vnvOOfGj26hVfx232SQZA/YZYTqqyRxpt1Bn3+V65oE5hkIk8Cpedkm+gPhN n4wG7gZvBxrUpranFA2Ftrq8nAsqJx9gyLznnKuzp2dO5pR+1a3SQzJ/FuQqCUwOxm wRvJyZPZhqakZN0+/6WeqwmAL9ZmFQXUG7Vn05rSRmDcRIOyTyIAoOg/DmeQ+K7ld8 ldlNy39C7slc+HhD9NjSU/CE/wumj1fALa8MWGdtg+oJJCRiduh1QP6a/NDwXgznJ2 uScUv0i+u7/BOOM1UXpgX3yvQZfejsBwktSTSmlCPvP2TPIHsH/tvRtmdWVQ0EIP21 pyLCspLJTNEcw== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1wzbk3-00000008PGy-2onS; Thu, 27 Aug 2026 11:10:11 -0400 Message-ID: <20260827151011.539857810@kernel.org> User-Agent: quilt/0.69 Date: Thu, 27 Aug 2026 11:09:55 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Deepanshu Kartikey , Haotian Zhang , Hui Su , Vincent Donnefort Subject: [for-linus][PATCH 6/7] samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify References: <20260827150949.304280511@kernel.org> 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 From: Haotian Zhang ftrace_direct_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_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. Link: https://patch.msgid.link/20260826015034.10755-1-vulab@iscas.ac.cn Fixes: ae0cc3b7e7f5 ("ftrace/samples: Add a sample module that implements modify_ftrace_direct()") Suggested-by: Steven Rostedt Signed-off-by: Haotian Zhang Signed-off-by: Steven Rostedt --- samples/ftrace/ftrace-direct-modify.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c index 1ba1927b548e..164d9dd6fd92 100644 --- a/samples/ftrace/ftrace-direct-modify.c +++ b/samples/ftrace/ftrace-direct-modify.c @@ -320,9 +320,15 @@ static int __init ftrace_direct_init(void) ftrace_set_filter_ip(&direct, (unsigned long) my_ip, 0, 0); ret = register_ftrace_direct(&direct, my_tramp); - if (!ret) - simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); - return ret; + if (ret) + return ret; + simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); + if (IS_ERR(simple_tsk)) { + unregister_ftrace_direct(&direct, my_tramp, true); + return PTR_ERR(simple_tsk); + } + + return 0; } static void __exit ftrace_direct_exit(void) -- 2.53.0