From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.4]) (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 C74BE47D44D; Fri, 7 Aug 2026 15:43:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786117404; cv=none; b=WgO9cdjcq1fk7IppQMOq8RymaGxPPhr6P+TLIZplqhuZgepVZrr5zT/ccolM4PiEInofz0ngsy2Fi5pqGITzA7RqmPIHjkHsgVqEHIx7cHL4YYRs9hSLM9B8pMHxWO8ivqfH+quZqu7RvFuUFQY/UYIXR+Jj3BBhdktM6AifFr8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786117404; c=relaxed/simple; bh=5BwIXjNXOqIB3B5MrRmGoSzyplQVb3VXUkGn9Eu6Qcc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=L27v1I1nZrRtTT+SyeMeUgVJTanBn1uyTphpYUvHUlpf3CZCAETgkIsoubYFot/+nsR5YXGIQ7m1MQGmgRnNh3sI260TiFfBE6MmAZO6igbER/Km7IfF9v2dyvFLSCdZnyTQp+2qPOtENtBGtMdPMdO5gPiWqdfYIIkGdfr6T80= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=Zru8Dznm; arc=none smtp.client-ip=117.135.210.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="Zru8Dznm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=Nh su+hO92dsCdty2EoE+vFnRNquHPYHyd8w06LW7iqM=; b=Zru8Dznm0nGuL1Fv1t ZTeErClmWwlvhYYNdCZWlC6FgErHeGo5nu/gj5FMOriLZ6XximrIdtrczgmQVyvO 3QfDkhSQrsm/FrJvX9pA9zot/7n0QgNMF8JKaPvP/hdI8GPLSo/rndVvGFoAkbFh wdGubhZpZK2ErwgR6JECKaqK0= Received: from localhost (unknown []) by gzsmtp4 (Coremail) with SMTP id PygvCgA3XrHy_HVqPDDBLA--.8549S2; Fri, 07 Aug 2026 23:42:43 +0800 (CST) From: Hui Su To: rostedt@goodmis.org Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Hui Su Subject: [PATCH] ring-buffer: Fix crash passing ERR_PTR to kthread_stop() Date: Fri, 7 Aug 2026 23:41:46 +0800 Message-ID: <20260807154145.2846521-2-sh_def@163.com> 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: 8bit X-CM-TRANSID:PygvCgA3XrHy_HVqPDDBLA--.8549S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7ZrWrKw4DZr1DZw17Gr13XFb_yoW8AF4xpr W5KF4UKr48AF4kZw4Uu3WF9ry7JFs8Z3W7Gr97Aw1rJF1UKw45Xr9xZFyYqrWqk3yrX343 Kr98XrWvkan8ZaUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0pRHCJkUUUUU= X-CM-SenderInfo: xvkbvvri6rljoofrz/xtbCwRNz0mp1-POEBAAA3j In test_ringbuffer()'s out_free cleanup loop, the check `!rb_threads[cpu]` only catches NULL entries and misses entries that hold an ERR_PTR. rb_threads[] is static, so unassigned slots are NULL. But when kthread_run_on_cpu() fails for a cpu, it stores ERR_PTR(-ENOMEM) (or -EINTR) in rb_threads[cpu] before the creation loop jumps to out_free. That entry is non-NULL, so the old `!ptr` check does not break, and the cleanup proceeds to call kthread_stop() on the ERR_PTR. kthread_stop() then dereferences the bogus pointer, crashing the kernel during the late_initcall self-test. crash logs: BUG: kernel NULL pointer dereference, address: 000000000000001c Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 1 Comm: swapper/0 Not tainted 7.2.0-rc6-dirty #7 PREEMPT(lazy) RIP: 0010:kthread_stop+0x2e/0x220 RBX: fffffffffffffff4 CR2: 000000000000001c Call Trace: test_ringbuffer+0x1ec/0x650 do_one_initcall+0x6c/0x2c0 kernel_init_freeable+0x21d/0x420 kernel_init+0x15/0x1c0 ret_from_fork+0x21b/0x320 Kernel panic - not syncing: Fatal exception Fixes: 64ed3a049e3e ("ring-buffer: make use of the helper function kthread_run_on_cpu()") Signed-off-by: Hui Su --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8e2485bb3aa8..6af7e36ca526 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -8214,7 +8214,7 @@ static __init int test_ringbuffer(void) out_free: for_each_online_cpu(cpu) { - if (!rb_threads[cpu]) + if (IS_ERR_OR_NULL(rb_threads[cpu])) break; kthread_stop(rb_threads[cpu]); } -- 2.43.0