From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793210230; b=vJb+MWcXCJxi+ew/loNi9UIIN8zHab8AVLwxT/q0PjNmZ1GP6k6Ur6SvK8Fq+t/SXoiW 1LkmVoCebxJODLmXVeITull5VpVfhA81VsonoglkyO++/rvBErkDKapZcvW+7vtk7fyC8 E7WL//b8IailESMXYy3Uaz8NB1Yf+g6nqenDysSjSYLBdWioTxECXI4cMbqW5xEDNot3b QH3tMnWsPvfgaJnHrmwt6V+mnomf4/Hjnr74bud0QoxR94Ss4mptXLUQUm+TsVsfwW2Gp II9sHw4eZCS0/7L1BV+CuS973YLD1/pLSRi3SmK+657qLcFyxtCHoEYUlaoslJnfd8g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210230; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=t5RZbts1/8vax1BKQLyxHozeVpq5ewcITmhpjrIDnRM=; b=jFghQ378X+Sa7NjXjn/MJ7+BPyAt4NdZEeepunh9PD0r13GD8JiVJIpIYLjiCAxdBTA4 KK8HR/TL3IkA1MjDQuXzqc+sE42aF1St9PWo+uopBToYzexSIGdI28iTdS7UzNvwRms2h 1DhwRm7yRpjaqUroXIBZVNhiP63NNAhma7VsLURoFvduHKnelccpIpQ3yi8cMQcCDPVs+ EuRZga/UqxyvEuCrtNUF3l5+4QruV5FUVh7KtXqYP518KOBRbOod4piI5a7KrPkuU+Nik T2uT4kJzTs6celEBcGACvTbR+Hw1bAzgaIluHo8oovhHipwMUBOzuCOOS0vtO0PRHGQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=FJtboycu; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0126606A327; Wed, 28 Oct 2026 17:57:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=FJtboycu Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CD4E1F01825; Wed, 28 Oct 2026 17:57:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210229; bh=t5RZbts1/8vax1BKQLyxHozeVpq5ewcITmhpjrIDnRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FJtboyculwp4frJiw2ypcTX5lVZ6UoVFX42BokrOUsOx1tl1V599kxK4nmMMCyZWQ VwLj5DvOxuVsiCYBCyxNCyZC/BK5d7LrASzB8AZ0YJQ4NQVijS3rp5E9FIgF/jGRGI /LzDUQzihwfG8AXmbe6xAxCgoxSvX10ZjHRwR2YY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Donggeun Yoo , Tom Zanussi , Steven Rostedt Subject: [PATCH 6.6 122/168] tracing: Save the event file instead of the compatible histogram Date: Wed, 28 Oct 2026 18:00:58 +0100 Message-ID: <20261028165945.974106760@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165943.089486480@linuxfoundation.org> References: <20261028165943.089486480@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Donggeun Yoo commit d5c42664fc094899af9aae5300b27fe8fdb658ef upstream. create_field_var_hist() creates a histogram on the matched event to supply a field variable, and records it on the target so it can be torn down later: hist_data = find_compatible_hist(target_hist_data, file); ... /* Save the compatible histogram information */ var_hist->hist_data = hist_data; hist_data is not the histogram it creates. It is one that was already there, whose keys the new one copies. The saved pointer has a single user, unregister_field_var_hists(), which runs when the target is removed: file = hist_data->field_var_hists[i]->hist_data->event_file; find_compatible_hist() matches on keys alone, so it can pick one with no variables of its own. check_var_refs() then returns false and the user can remove it while the target still points at it: BUG: KASAN: slab-use-after-free in event_hist_trigger_free+0x2b2/0x320 Read of size 8 at addr ffff8880093b90e0 by task init/1 Freed by task 1: kfree+0x154/0x420 event_hist_trigger_free+0x1d5/0x320 event_hist_trigger_parse+0x35f3/0x69e0 trigger_process_regex+0x1a6/0x250 Save the event file instead. It is all the dereference ever wanted, and it does not go away when the user removes a trigger. Cc: stable@vger.kernel.org Reported-by: Sashiko Link: https://lore.kernel.org/all/20260914110753.221E61F000FF@smtp.kernel.org/ Link: https://patch.msgid.link/20260914234754.3676905-1-donggeunyoo.kernel@gmail.com Fixes: 02205a6752f2 ("tracing: Add support for 'field variables'") Signed-off-by: Donggeun Yoo Assisted-by: Claude:claude-fable-5 Acked-by: Tom Zanussi Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_events_hist.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -542,7 +542,7 @@ struct field_var { }; struct field_var_hist { - struct hist_trigger_data *hist_data; + struct trace_event_file *file; char *cmd; }; @@ -3077,8 +3077,8 @@ create_field_var_hist(struct hist_trigge return ERR_PTR(-ENOMEM); } - /* Save the compatible histogram information */ - var_hist->hist_data = hist_data; + /* Needed to remove the histogram when the target goes away */ + var_hist->file = file; /* Create the new histogram with our variable */ ret = event_hist_trigger_parse(&trigger_hist_cmd, file, @@ -6300,7 +6300,7 @@ static void unregister_field_var_hists(s int ret; for (i = 0; i < hist_data->n_field_var_hists; i++) { - file = hist_data->field_var_hists[i]->hist_data->event_file; + file = hist_data->field_var_hists[i]->file; cmd = hist_data->field_var_hists[i]->cmd; ret = event_hist_trigger_parse(&trigger_hist_cmd, file, "!hist", "hist", cmd);