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=1793207923; b=cSxELTvgA/bM36nuJu3a4Vr1p9K6mkMn2k4/uKnPaqNo40ShmGbVgkcv58vaGHEpMs5V 0dqGjQ7G5KIu0inZAx6R2Kx4RKqLN92dnWwGG8Zr2/TObUDoYAAAPUw3QGZlDx5RzuoIL W7KeAj5iP+E0uwdXjT14qhVPQavU2fSZJd7NG/PZ/1TvS8ccWXQo5ibjcUOJ61MuGLIbJ T7TK9MmZbVIxnYjfzdCD40JP0HP/UvBk3MKwCGaec8z5Nci6MnwR/OUrkXZSsPmvZXQhb cwlr4s7hj4QLKdZYEDluW0Vibwh9+DEyDu7FgtPB2bdK84imZMiz0SN79sftIRcXFCA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793207923; 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=No0qZF9cM1+9RGS4Zz4ajE18B7To3+tBnTC/5sVdSXI=; b=Nf93qSfQibKOtG3MiANk8g3kb2TljdAAbrRx+YbDRZr0LjieaochicfJR/6kKJIn0OZ4 xy1bwhrXU/+ZyKnksZ6Si+NW2s+6RwPQnvUMSXlxI/M1iMLYEemkTLSUXMR1fcOu3oyc3 twGQM4WfVPquhm9PjZ4mZajnlmMejS2q7fOkyslG6QJxcj660CxvWcJNbC2JnP2ozR2U+ +nckGsMXMAW9m3PzkbsNj50UNgd7QMN80NBZtXUBT+YyogRA8H+a3z0ShrxjtqO0z7wZy ihXR1MyXp/3aDFg76FE6ZwHhf0bjmVrFcYPwAfvrW60S8PmJI1OytHvleYz7iQ7botQ== 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=ISr3wGfs; 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 6052D606A321; Wed, 28 Oct 2026 17:18:43 +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=ISr3wGfs Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABA331F031E1; Wed, 28 Oct 2026 17:18:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793207923; bh=No0qZF9cM1+9RGS4Zz4ajE18B7To3+tBnTC/5sVdSXI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ISr3wGfstDO7DMZEhJfReo8eEc+u1OvhiHeC2oMX9z2zSRqQqyOICbnFkTdRgw28H txKhVaPcjgYwsOhM01dzaB0Pfbzr6H+DosQSD3Zd3wFacEHeDvniJb9ih/h/Gn4iOJ IiqZHTI9kqeKDApQCEHia9zEgitHJShiDQSfQrUg= 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 6.12 188/247] tracing: Save the event file instead of the compatible histogram Date: Wed, 28 Oct 2026 17:59:51 +0100 Message-ID: <20261028165951.871461488@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165947.349197979@linuxfoundation.org> References: <20261028165947.349197979@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 6.12-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, @@ -6299,7 +6299,7 @@ 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);