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 6CF49477995; Thu, 27 Aug 2026 15:09:23 +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=1787843365; cv=none; b=XwXIIFS9JZyWKAgrUuBnhc3Mke5OtokBbV52PO2FhEZhtX47sZlWuGRe7psXZxQ5lA6MO24LoKDgecFCx73S1d9VZRLp44CNzrSVRsnta0SFgtYYFQj0YAKKeSFrw1PKoFQ6EK2livtmAd7xhkr0de1IA9umvcXUrZl4vOww/E8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787843365; c=relaxed/simple; bh=JPELbtqDwmev8QYHC4CJVOnU1QVGCPg6zDW7t3hN2BI=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=pO07s3q2HhDihoQOb4sm11/H2Pym8eW+ctYec1nEuzIyqR02DzHBr/YrVDq665dnGIND+6GPUsnZ8iheAVUEEqOtvjil26mI2YucXHC52mr/uMb8UUg2EGs9k8eM2vjKrgG1/8ec7ThoQZvbG//wLmuLgsDDp5euDLuuFXnyzww= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M2dFF7+2; 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="M2dFF7+2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2AC9E1F00A3D; 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=5EI51HQq89GNPsww2hRYcznaJIDs1nehxu0amxKuebQ=; h=Date:From:To:Cc:Subject:References; b=M2dFF7+2iJR3VaGO+VmUr/x0KYGvHzQJoodyYFFpjxLXMyCGdp9mwSSujt7AcoUAU +oR9HKyUGgBjdFcVlblHEydPKb/UTsspMbXPJKXpK+aOtgrJDN2STTtpfa33G1CSg6 hoJX/0dbLdT0tg7uwmcJpv4DdzQobI+0ieNG0cFenzYpYMNZRJgNG7bOF12oOHrH8N pVVPVcOKAs6mAWrO3NongioS+zSjQ3UvmJDd/YEt9OBP4nRZ2ecaiZFqm8RWVq8bn3 GhR4Dt6lvJM6YmwVQxkMiIKzsCjVOMDXZjptjJA8BOFn8rpHbc7iGLS2mPuG+GToV7 dILqDrtEaJMXA== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1wzbk3-00000008PF2-0E0v; Thu, 27 Aug 2026 11:10:11 -0400 Message-ID: <20260827151010.884247572@kernel.org> User-Agent: quilt/0.69 Date: Thu, 27 Aug 2026 11:09:51 -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 , stable@vger.kernel.org Subject: [for-linus][PATCH 2/7] tracing: Fix use-after-free with same-name named triggers 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: Hui Su When two hist triggers on different events are registered with the same name=, the second one reuses the first as named_data. Both are added to tr->hist_vars by save_hist_vars() during event_hist_trigger_parse(), because save_hist_vars() is called before event_trigger_register() while the named reuse is only detected later, in hist_register_trigger(). In the named-data branch hist_register_trigger() then frees the second histogram's hist_data via destroy_hist_data(), but never removes its tr->hist_vars list entry, leaving a dangling pointer and leaking the trace_array reference it holds. A later hist trigger that references a variable makes find_var_file() walk tr->hist_vars and dereference the freed hist_data. The bug is reproducible from userspace by writing three hist triggers to tracefs: cd /sys/kernel/tracing echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_switch/trigger echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_process_fork/trigger echo 'hist:keys=common_pid:vals=$x' > events/sched/sched_process_exit/trigger The third write panics the kernel: BUG: KASAN: slab-use-after-free in find_var_file.part.0+0x272/0x290 Read of size 8 at addr ffff888001f8a0e0 by task sh/1 CPU: 1 UID: 0 PID: 1 Comm: sh Tainted: G D N Call Trace: find_var_file.part.0 find_event_var parse_atom parse_expr __create_val_field event_hist_trigger_parse trigger_process_regex event_trigger_write vfs_write ksys_write do_syscall_64 entry_SYSCALL_64_after_hwframe Allocated by task 1: event_hist_trigger_parse Freed by task 1: hist_register_trigger+0x618/0xa30 event_hist_trigger_parse The buggy address belongs to freed 2048-byte region Oops: general protection fault ... RIP: find_var_file.part.0 Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b Fix by removing the hist_data from tr->hist_vars and releasing the trace_array reference in the named-data branch of hist_register_trigger() before freeing the hist_data. Cc: stable@vger.kernel.org Fixes: 6f86bdeab633 ("tracing: Fix bad hist from corrupting named_triggers list") Link: https://patch.msgid.link/20260816100427.33642-3-sh_def@163.com Signed-off-by: Hui Su Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_hist.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 893bd8b0e48a..963e0d6b61fd 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -6661,8 +6661,10 @@ static int hist_register_trigger(char *glob, tracing_set_filter_buffering(file->tr, true); } - if (named_data) + if (named_data) { + remove_hist_vars(hist_data); destroy_hist_data(hist_data); + } out: return ret; } -- 2.53.0