From nobody Mon Sep 28 05:45:30 2026 Received: from cstnet.cn (smtp21.cstnet.cn [159.226.251.21]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9706449362C; Wed, 26 Aug 2026 01:51:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.21 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787709068; cv=none; b=D2RZn5sei4mmR/jIBjhWhZXWN8PpQQQZeYvAIJn0GiauBol+QzUJu/vDMYJtvH5PVIB16JgOrvFBAGRoCTbPFrmrECmXm+ryAEbcV6xL+2neRTc8piIKkNnino8k5GIujb8ApkaCAJoJm1Xvw7rqlIFepGqDtfUi+Bo3Dm9IhzA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787709068; c=relaxed/simple; bh=BvjD+j7aMJ9r5B0+nQUZfAHKMYEoyfe+Fndtfzx5GU8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=dHBZtmP1n8b8AeUddkBh03rUlhuGbxQ/psS4xOVkeVltbUoKBo93GcPivwceOthxm+8DZjQugZQ3tL1PttnnsvtStYEOaKtD/W4IISD572mOYvABSWrgJ8sl4iaw+uNSsR3jx8ioIFUaCKl6c0u1fEs6tcWABAgVOOfe+uax8vs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from DESKTOP-L0HPE2S.localdomain (unknown [36.110.52.2]) by APP-01 (Coremail) with SMTP id qwCowAAn_vGDRo5q_E6QBg--.47910S2; Wed, 26 Aug 2026 09:50:59 +0800 (CST) From: Haotian Zhang To: rostedt@goodmis.org, mhiramat@kernel.org, mark.rutland@arm.com Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Haotian Zhang Subject: [PATCH v2] samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify Date: Wed, 26 Aug 2026 09:50:50 +0800 Message-ID: <20260826015050.10772-1-vulab@iscas.ac.cn> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qwCowAAn_vGDRo5q_E6QBg--.47910S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WrW5Xr18urW8Cr4fCw43GFg_yoW8ArWrp3 y7u3sxKr1rAFZ2gF9ruF17Cr17A347ArWUC3s5A3yYvrsxurWUJryjyF90qF4xArWrKFW7 Zrs0yrWkJF45ZaUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9a14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjcxK6I8E87Iv6xkF7I0E14v26F 4UJVW0owAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv 7VC0I7IYx2IY67AKxVWUtVWrXwAv7VCY1x0262k0Y48FwI0_Jr0_Gr1lYx0Ex4A2jsIE14 v26F4j6r4UJwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2 zVCS5cI20VAGYxC7MxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAKI48JMxC20s026x CaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_ JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r 1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_ Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8Jr UvcSsGvfC2KfnxnUUI43ZEXa7VUjWrW7UUUUU== X-CM-SenderInfo: pyxotu46lvutnvoduhdfq/1tbiBwgLA2qOJu5mVwAAsa Content-Type: text/plain; charset="utf-8" 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 modif= y interface") Suggested-by: Steven Rostedt Signed-off-by: Haotian Zhang --- Changes in v2: - Simplify the code as suggested by Steven Rostedt. --- samples/ftrace/ftrace-direct-multi-modify.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/f= trace-direct-multi-modify.c index 8f7986d698d8..70c2263d839c 100644 --- a/samples/ftrace/ftrace-direct-multi-modify.c +++ b/samples/ftrace/ftrace-direct-multi-modify.c @@ -364,9 +364,15 @@ static int __init ftrace_direct_multi_init(void) =20 ret =3D register_ftrace_direct(&direct, my_tramp); =20 - if (!ret) - simple_tsk =3D kthread_run(simple_thread, NULL, "event-sample-fn"); - return ret; + if (ret) + return ret; + simple_tsk =3D 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; } =20 static void __exit ftrace_direct_multi_exit(void) --=20 2.43.0