From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cstnet.cn (smtp81.cstnet.cn [159.226.251.81]) (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 6B5183911A8; Tue, 25 Aug 2026 09:34:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.81 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787650494; cv=none; b=TaqkN4wsO/qq5YCFwL89o62u1JpFULC9hTQgaajupmkk+EUvlAz2OAIOxjVzAU6eCPB0RfcpFirW5PiI7uj4PlOjs5CavpQPRfP875P98VAEUHhM/2uFYJqra061VY3NJFLtNtzETosOp3Yyfs44AbKmv0KO4PGyZWqmmGSqqp0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787650494; c=relaxed/simple; bh=MYYAtIKcEDrWA8i/EN1vxPSf/AmntErOIHt32HAZyRw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=GCZJtbA6eyR0Z7qxM46EsBHkNUWrQpL7mcu60JYmnJR0+b3MY+YEWV9uvnsrOgvVy+byQBOTWojKb1QUX5tnPrDl2Lj3LF72CCKyNyE3VF7EbfUZUYUbrht3MkSGlDb1n4e0xzG+panNZJW5quOWV/5mW/NrQXLOQPqvn0dQyr4= 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=159.226.251.81 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-03 (Coremail) with SMTP id rQCowAC3vTu2YY1q4X46Bg--.38100S2; Tue, 25 Aug 2026 17:34:46 +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 2/2] samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify Date: Tue, 25 Aug 2026 17:34:41 +0800 Message-ID: <20260825093441.7394-1-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:rQCowAC3vTu2YY1q4X46Bg--.38100S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WrW5Xr18urW8Cr4fuF45Wrg_yoW8Xr1kp3 ya93sxWryFyFZ7KF97uFnxCr17A34UJrWUCas3A3y5Zws8Cr4UJrW2yF9Iqr4xAryFyrW3 Zrs0yrZ5JF45XaUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkC14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAFwI0_Cr0_Gr1UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lc7CjxVAaw2AFwI0_ JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67 AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIY rxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14 v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8 JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUOWrWUU UUU X-CM-SenderInfo: pyxotu46lvutnvoduhdfq/1tbiDAAKA2qNIA79awAAsa 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()") Signed-off-by: Haotian Zhang --- samples/ftrace/ftrace-direct-modify.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c index da3a9f2091f5..2795ea12cdf9 100644 --- a/samples/ftrace/ftrace-direct-modify.c +++ b/samples/ftrace/ftrace-direct-modify.c @@ -320,8 +320,13 @@ 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) + 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; } -- 2.43.0