From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=216.40.44.11 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792855083; b=cqvIQcUmiOYNX9Nheg9v4LrQRy+ue8GD5ZZvVEt8ztA2ESEn2p+6q0wH5rlWj/VCtEsC i1TQCQ1hPGlp0Nz8fXl+vZPLYalRd2yCs6yy0DGLvPdY6q+7JlcAfYf7/Wbj1q7sQDIxJ d7krPAa57izLgqBOP3Vrpwb1McSXre21bsEQSZV87pw0YKpdkzQ6HziUv8kbr+YldgW0l lz+i5TDFiyNpqOZT0to5R9FOv3o1l3kOEzcasH+7xCZehUI46e/SMhPG9zwWTHB0EqMGS Ebc7DOcbiGHD898MLmfIOOZE/16Q6K5uD5RMKf9QnnCbqZGtgh5xPzrLLVvEXwIst3A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792855083; h=DMARC-Filter:Received:Received:Date:From:To:Cc:Subject:Message-ID: In-Reply-To:References:X-Mailer:MIME-Version:Content-Type: Content-Transfer-Encoding:X-Rspamd-Server:X-Rspamd-Queue-Id: X-Stat-Signature:X-Spam-Status:X-Session-Marker:X-Session-ID: DKIM-Signature:X-HE-Tag:X-HE-Meta; bh=FFBc7sAZT89TLlAdtb/PifRoSe8BnNHwA0EhAG89FeQ=; b=QtQPDnFFc7SsdO5MZv242/Uv0xjIfUgndh0EXjT7Mt26gCrfrKbDQ1HOeE64drmaD8td skKZAmOvytMTsMTtsF9PwBH3emyTalbNzGuNFjH0tC4wmIQx/AmzGGJhooA3L9QNt9jzc FLEx/yUcKjsVh4a8Obb2j4AXx9P3REL0qnHNWiwxTwu0vgLODZn9Auv8brdRlEhFJtPoM Nau1kS4oHh85Gkomvlfsrm9ERvY2eNaOHzx45LFkxYEVfpk5Qy55io2H/syEEL7PE4Xkp RKUS/KUVn1A1uWkwSH2f7wSCL/wuBsa9i6iBHSoNR/DnXjL6hO1g5OIC9n/L2AKsOog== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; dkim=pass header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b="GMcLN/iF"; arc=none smtp.remote-ip=216.40.44.11 Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B4F5A606A31A; Sat, 24 Oct 2026 15:18:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org B4F5A606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b=GMcLN/iF Received: from omf03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 4C1A8160425; Sat, 24 Oct 2026 15:18:01 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf03.hostedemail.com (Postfix) with ESMTPA id 72C736000A; Sat, 24 Oct 2026 15:17:59 +0000 (UTC) Date: Sat, 24 Oct 2026 11:17:56 -0400 From: Steven Rostedt To: Guikun Yang Cc: Masami Hiramatsu , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [BUG] tracing: trigger filter use-after-free in set_trigger_filter() ENOMEM path Message-ID: <20261024111756.14a393ac@fedora> In-Reply-To: References: X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout03 X-Rspamd-Queue-Id: 72C736000A X-Stat-Signature: 3rhrjhr117dfn7ztage4iwijjcaun5qa X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+t5tM3VmUu6Ah5SnRaSk/Nd4i7D2EA+lI= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=FFBc7sAZT89TLlAdtb/PifRoSe8BnNHwA0EhAG89FeQ=; b=GMcLN/iFd4+lKnEyemdZByvEiMKlyE9vk0QgGvSeEn0OB+6b5a9DGNs3nGqd9ete7GztBttU32SQan3DI002DafwZul6Bnu+Zq5Fe3KO93UL3U3DoxB7ohg8EJMgIgNI8+KKOGRKd34z3JhlabnIewc7bsmoLBVu8Iw0JRElPaQ= X-HE-Tag: 1792855079-985549 X-HE-Meta: U2FsdGVkX18wFkgskoivpNdycLjtFJ410q1WfoZfwxhO2tQ4A2sCOyNvhjqw/D/6qaT7CThd6/eyXIv1STZho0JqRJWejx21Nl3uDetSIBas/sJuM/wGbM5Yt5hgs0pcqMnR9UaZErWSlMfKRSzP59fImmmqbYvZj5thiFoTfVgFVRFvOAsVepACpfBE8koEOLIe6tMCfCzU2+01jaAR1A1FiACMSrkFZpBm34Cv3IbiTsICSydTkddCfUvt3EdKc9FGCmvGwgQ/ah+LkDfFIgGhSz5RBvFKncMk0jhQwenwOPXtTGTYTChOTv8nSAFY/vlNyT1Zb8MqvSfmqG3j3Pg0TrKwMHcH On Sat, 24 Oct 2026 22:48:16 +0800 Guikun Yang wrote: > Fix: either free the new filter before publishing (i.e., don't > rcu_assign_pointer until the filter_str copy succeeded), or perform > tracepoint_synchronize_unregister() before free_event_filter() in the > ENOMEM path, mirroring the normal path. The first variant is > cheaper: move the kstrdup above the "assign:" label and release the > pointer only after the string copy succeeded. Note, the entire trigger code needs a rewrite. Something I'm looking at doing when I get time. This is a bug but one that would be very hard to hit as it would require and admin to enable a trigger with a filter during major memory pressure. That said, the simplest fix is to simply copy the filter_str at near the start and use that. That is, something like this (not even compiled tested): diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index 4d2fde996c0f..1a6ea4261066 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -1195,6 +1195,7 @@ int set_trigger_filter(char *filter_str, { struct event_trigger_data *data = trigger_data; struct event_filter *filter = NULL, *tmp; + char *str __free(kfree) = NULL; int ret = -EINVAL; char *s; @@ -1209,9 +1210,13 @@ int set_trigger_filter(char *filter_str, if (!filter_str) return ret; + str = kstrdup(filter_str, GFP_KERNEL); + if (!str) + return -ENOMEM; + /* The filter is for the 'trigger' event, not the triggered event */ ret = create_event_filter(file->tr, file->event_call, - filter_str, true, &filter); + str, true, &filter); /* Only enabled set_str for error handling */ if (filter) { @@ -1243,14 +1248,9 @@ int set_trigger_filter(char *filter_str, kfree(data->filter_str); data->filter_str = NULL; - if (filter_str) { - data->filter_str = kstrdup(filter_str, GFP_KERNEL); - if (!data->filter_str) { - free_event_filter(rcu_access_pointer(data->filter)); - data->filter = NULL; - ret = -ENOMEM; - } - } + if (str) + data->filter_str = no_free_ptr(str); + return ret; }