From mboxrd@z Thu Jan 1 00:00:00 1970 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 E65BC49362C; Wed, 26 Aug 2026 01:50:52 +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=1787709057; cv=none; b=efYzJjP3QHHCCnvCUV7yXgQTJmc1yT5DDrdei6wBS2M6R+osLP8Pt23eE/k8NfpL/cRlWACwLRALzkPJqhaKf4V4dytqkbr09oBzfBNb97y+ps1eTiV1OEpPM1F1YcavhVXFXRHs7qKWiFu5lYesetR68ei6DZbfateyYR3Hv+I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787709057; c=relaxed/simple; bh=9FmTLGbwPOSWXwTOimREj523u0JvJkLMeaGZ8fP0afI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=PxtpE307eCgknmPmP5Ep8FgzDjiPgJluqBqSCXFqpcAeFm4whlK9avUisuvJhxpBci5k7xud3eOcltlqfVdXY8fisFaJSC9LZPRzgrgOfD+EJ40moXm/jlWCbx2cd6er7z5C+vPE1TX4V5tdZSZBgebRkTo+vdascoyvHvDWhAI= 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 qwCowADnvPByRo5q2E2QBg--.13826S2; Wed, 26 Aug 2026 09:50:42 +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-modify Date: Wed, 26 Aug 2026 09:50:34 +0800 Message-ID: <20260826015034.10755-1-vulab@iscas.ac.cn> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:qwCowADnvPByRo5q2E2QBg--.13826S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WrW5Xr18urW8Cr4fuF45Wrg_yoW8AF1fp3 y3u3sxKr1YyFZ2gF9ruFnrCr17A34xJrWUC3s3A3yYvws8Cr4UJrWjyF9Iqr4xAry0gFW3 Zrs0yrW8AF45XaUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9I14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjcxK6I8E87Iv6xkF7I0E14v26F 4UJVW0owAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv 7VC0I7IYx2IY67AKxVWUtVWrXwAv7VCY1x0262k0Y48FwI0_Jr0_Gr1lYx0Ex4A2jsIE14 v26F4j6r4UJwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2 zVCS5cI20VAGYxC7MxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAKI48JMxC20s026x CaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_ JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r 1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_ Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVWUJVW8Jb IYCTnIWIevJa73UjIFyTuYvjfUerWFUUUUU X-CM-SenderInfo: pyxotu46lvutnvoduhdfq/1tbiCRILA2qOJHVrAAAAsN 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. Fixes: ae0cc3b7e7f5 ("ftrace/samples: Add a sample module that implements modify_ftrace_direct()") Suggested-by: Steven Rostedt Signed-off-by: Haotian Zhang --- Changes in v2: - Simplify the code as suggested 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 da3a9f2091f5..246a8b9b22ce 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) -- 2.43.0