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 28F753806DA for ; Wed, 16 Sep 2026 14:21:03 +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=1789568464; cv=none; b=GxnjoqVvKvoyWC+OuBFq1bVmYli9jZhiHcbYUBjC77dLrpUT1XRYTrw39/Xoc9lbQfzlwM1wFO+TkdV8ihs/K20Mo0Md4JM8VtIEewewlwmMCCBHm2QsPTNfQGdcG4SqJogvLcUogERLgIeHDJ7kK7UktgwySQUaHuw88hWCepQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789568464; c=relaxed/simple; bh=SGDVTpTwe0BMk+WV/J6k22GS/TbYm4MCkGuesrRSk08=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=uz9whoq6gqN8uRDT9uWrEXcdkjvNcNxL+il3Yq98Jkxlh3h4rxSSz4vgY6G9S3Ys1xu4yNXNf6ZvLaUtqOR15+5pK1xEnfUNI03asn8fnVsiQ/au6r4EE2ssxVv4vnfKSVuaQRLN95O2rnI+eA1J8ketX65Kr44Tt5FnPHt939U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=w4otBbuE; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="w4otBbuE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EBAA1F000FF; Wed, 16 Sep 2026 14:21:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789568462; bh=qLwjhvB8MfoBJbmuSZSJk0lGUF1IYpwrE7HSRWCdj1k=; h=Subject:To:Cc:From:Date; b=w4otBbuEI7PdIGdfzm25xxF+7MhNUFNZB/CUGoOob0pMFgFA+sm0OAH/+8QoVRDE5 A2ptFqTC4sbbut2BLTwYBh5sLQUxdIe3DsbKJYswN0djlcZ1Jsrh4dKyVzuNPO0kKo XcyVBghUMbDAGmNmai7KC2CHrQ3EwYG4k8dhPotY= Subject: FAILED: patch "[PATCH] tracing: Undo the registration when enabling the histogram" failed to apply to 6.1-stable tree To: donggeunyoo.kernel@gmail.com,rostedt@goodmis.org,sashiko-bot@kernel.org Cc: From: Date: Wed, 16 Sep 2026 15:19:04 +0100 Message-ID: <2026091604-putdown-resort-2cec@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 92383cef66791a0c63a2f27755cadbdb2fbf270b # git commit -s git send-email --to '' --in-reply-to '2026091604-putdown-resort-2cec@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 92383cef66791a0c63a2f27755cadbdb2fbf270b Mon Sep 17 00:00:00 2001 From: Donggeun Yoo Date: Mon, 7 Sep 2026 21:44:20 +0900 Subject: [PATCH] tracing: Undo the registration when enabling the histogram trigger fails Commit 6f86bdeab633 ("tracing: Fix bad hist from corrupting named_triggers list") described how a trigger that is registered but not on file->triggers ends up freed while still on the global named_triggers list, and moved the registration down so that hist_trigger_enable() follows it immediately. One path still gets there. hist_trigger_enable() adds the trigger and takes it straight back out when the event cannot be enabled: list_add_tail_rcu(&data->list, &file->triggers); update_cond_flag(file); if (trace_event_trigger_enable_disable(file, 1) < 0) { list_del_rcu(&data->list); update_cond_flag(file); ret--; } so the list walk in hist_unregister_trigger() matches nothing, test stays NULL, and the ->free() that would call del_named_trigger() is skipped. out_unreg falls through to out_free, which frees the trigger anyway: BUG: KASAN: slab-use-after-free in find_named_trigger+0xac/0xc0 Read of size 8 at addr ffff8880091d3160 by task init/1 find_named_trigger+0xac/0xc0 hist_register_trigger+0xc1/0xa00 event_hist_trigger_parse+0x3146/0x6af0 event_trigger_write+0xce/0x160 Freed by task 69: kfree+0x154/0x420 trigger_kthread_fn+0xfd/0x160 Leave the trigger where hist_unregister_trigger() can find it and let that undo the registration, which is the only code that knows all of what cmd_ops->init() took: the named list entry, the hist_pad reference, the reference on the trigger a named histogram is shared with, and the copied cmd_ops. It also pairs the failed trace_event_trigger_enable_disable(), whose sm_ref and buffered event reference are otherwise left behind. Since ->free() releases trigger_data and, for a trigger that does not share its histogram, hist_data with it, out_unreg can no longer fall through to out_free. For a trigger that does share, hist_register_trigger() has already destroyed the caller's hist_data, so the fall-through was reading freed memory there as well. Move the enable_timestamps check in hist_unregister_trigger() above the ->free() call for the same reason: hist_data does not outlive it once the trigger being removed is the one that owns it. Cc: stable@vger.kernel.org Fixes: 067fe038e70f ("tracing: Add variable reference handling to hist triggers") Reported-by: Sashiko AI Closes: https://lore.kernel.org/linux-trace-kernel/20260907092944.3950E1F00A3D@smtp.kernel.org/ Link: https://patch.msgid.link/20260907124420.607097-3-donggeunyoo.kernel@gmail.com Signed-off-by: Donggeun Yoo Signed-off-by: Steven Rostedt diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 54c95f9bd0a3..53100287466f 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -6670,11 +6670,12 @@ static int hist_trigger_enable(struct event_trigger_data *data, update_cond_flag(file); - if (trace_event_trigger_enable_disable(file, 1) < 0) { - list_del_rcu(&data->list); - update_cond_flag(file); + /* + * On failure the caller undoes the registration, and + * hist_unregister_trigger() can only find the trigger here. + */ + if (trace_event_trigger_enable_disable(file, 1) < 0) ret--; - } return ret; } @@ -6752,13 +6753,13 @@ static void hist_unregister_trigger(char *glob, } } - if (test && test->cmd_ops->free) - test->cmd_ops->free(test); - if (hist_data->enable_timestamps) { if (!hist_data->remove || test) tracing_set_filter_buffering(file->tr, false); } + + if (test && test->cmd_ops->free) + test->cmd_ops->free(test); } static bool hist_file_check_refs(struct trace_event_file *file) @@ -6963,6 +6964,8 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops, return ret; out_unreg: event_trigger_unregister(cmd_ops, file, glob+1, trigger_data); + /* The unregister frees trigger_data, skip out_free */ + goto out; out_free: remove_hist_vars(hist_data);