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=1792678672; b=jIgurHNTWPvMLjpVvYXSmXYzl1Aj+eaUeH7es0l10Dwv40tJwc5r/wZEedhltv+gSSbW QAzc8OsKX94JX7sumtAVG3hDZwkAHrmfToO9fnGPggChjfJE59ZH9Sk7TmkTXQrUmw0Ms 9LfRHEIxKJz9il4qrACggj949rw6WffJ8tknZRZbwePbnZ6XxsTsErO59Bfh6A2U1xj7K EMbGR7rfbd74mIU1fZct9ygyAofv9fJhXkDxHWhtLVW4l7siCVMPUAHgSrrhuvtGbjk5q B9PyOKZppe7BdlGk5eQAMPkY7dxRCliixsLkQZpSHyLyqx+O6UcfYkxPPcBX4ZK+12Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792678672; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=KofXG14LZqiIaN7Gz529bQzE3SyVd3GZw16KGMgu6cY=; b=4zFfdJva30Mt2jlxRolvfoErwvk5NsNgjRxzYiEfM2jkmpcfYKjjS+/tleObdXa0iGKK LSF46fAefkt5AuXXPJjT9lNHxLcZg1jwlXqhjpTNCQOG79aTkeQ/6kWPeaspbeFV7EGY+ cTL9tYQKZJfK2admSgll+fbsJdUq0M7HEwGm0CtdLMx14i8K32NsGku0Cd7O2OWc09tuI nE0oKxyEgb6eBnn3VBZz3SOpelULpMtUaNVl5InjbfnHLRJ/sJaWdhok/pU+YZe9T9Vkr 0XEmvFwN+YHejaGslYa1zBE9iiyfAqwBqJqbYIjMqV2LS/rnfYzpqrktntobB/LhdlQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=fICNl4ip; 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 A5F4C606A31D for ; Thu, 22 Oct 2026 14:17:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=fICNl4ip Received: by smtp.kernel.org (Postfix) with ESMTPSA id B970E1F000C2; Thu, 22 Oct 2026 14:17:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792678672; bh=KofXG14LZqiIaN7Gz529bQzE3SyVd3GZw16KGMgu6cY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fICNl4ipzb/oqhj9/QcZc8bBQ32yheHE/Eqd3EocRjpCKC6ifFbAGGwV6HvFmbJsh J2dN/Kk5Hvu8x4DVkrDouhSIhiZQZjzjhf6zVF7KPtEBX/tW1WxmFk/aAEvHGs0FXU Ql4hYoS9hxMJlAHv/zQXesftv6p4pv7CWe8V2L0AAqQ42JIyIbFKLSoKgnyuV7H+Ne GTmfz9y1+u78Qfru1tMCIGl61Q5fkOEPP6tfA1QzLv/ZzpSY2G7hL9sjlVTpni5dMb YIg/VNdEC0GvgRewIIrqwypWpvQlFmxuPm/1RiTPwx9LY67S3bQXCwrHT6L7pfH0Cf ffgt9USW1XNiQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Donggeun Yoo , Steven Rostedt , Sasha Levin Subject: [PATCH 6.6.y 4/4] tracing: Fix NULL dereference when copying keys for a field variable Date: Thu, 22 Oct 2026 10:17:48 -0400 Message-ID: <20261022141718.1585988-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261022141718.1585988-1-sashal@kernel.org> References: <2026102123-crushable-fragrance-1b92@gregkh> <20261022141718.1585988-1-sashal@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Donggeun Yoo [ Upstream commit a0777b9e53157f1f6848a0fd0650f5465391ea81 ] In event_hist_trigger_parse() where it needs to create actions like "onmatch", it calls: event_hist_trigger_parse() { create_actions() { action_create() { trace_action_create() { trace_action_create_field_var() { create_field_var_hist() Where create_field_var_hist() does a loop on the hist_data representing the keys. The issue is, if the keys uses one of the pseudo field types (like common_cpu), the hist_data field element will have NULL for its field member causing a NULL pointer dereference when accessing the key_field->field->name. # echo 'hist:keys=common_cpu:ts0=common_timestamp.usecs' > \ events/sched/sched_waking/trigger # echo 'my_synth u64 lat; int prio' > synthetic_events # echo 'hist:keys=common_cpu:wakeup_lat=common_timestamp.usecs-$ts0:\ onmatch(sched.sched_waking).my_synth($wakeup_lat,prio)' > \ events/sched/sched_switch/trigger KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:create_field_var_hist+0x771/0x1380 Call Trace: trace_action_create_field_var+0x360/0x600 trace_action_create+0x393/0xe80 event_hist_trigger_parse+0x3e47/0x69e0 trigger_process_regex+0x1a6/0x250 event_trigger_write+0xce/0x160 Instead of accessing it directly, use the proper handler expr_field_str() to get the name. The three previous patches are prerequisites: without them a .buckets key and a common_stacktrace key each render into a command that cannot be parsed back. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260914053443.981201-5-donggeunyoo.kernel@gmail.com Fixes: 02205a6752f2 ("tracing: Add support for 'field variables'") Signed-off-by: Donggeun Yoo Assisted-by: Claude:claude-fable-5 Signed-off-by: Steven Rostedt Signed-off-by: Sasha Levin --- kernel/trace/trace_events_hist.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index a3b0a8fa428a8..1c4dff1031a0e 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -3060,7 +3060,7 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data, key_field = hist_data->fields[i]; if (!first) seq_buf_putc(&s, ','); - seq_buf_puts(&s, key_field->field->name); + expr_field_str(key_field, &s); first = false; } -- 2.53.0