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=1792676567; b=0FdJ7JUSPMjR6q5/99ZLly8GofIYoGYP2p5OFaNmb/x5X7nTw4LjUNndOcohH7hT+MAv l3MokJ46hjfUirDkEudh/y4OiHveG72NfV+VSsdcsig9ohoMC3YWlpZBzrKdjxcVSowV/ Ag8HGT+aU8CPjnCH/r4EKkSdmHm9faNwxkdNTpJzp2vC0GZ6oFZvb1n+18Z+z0d0lAfhL HaraOke6fs52XvZqLJ1MabvIWfes9DIwwhNxP6M/JxMvhWU7yddLaxyeK19jplINL1RFm EjZS6SGkkmFxoA/NVxQV46bXQk3WM7AENEfxG+m5qOc0/DpZu4DhYFVdsKoZCmS0zUQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792676567; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=s4AuCrYsn4dS2nLKpVvR0o43olVmPhMRKwWCMlr93FY=; b=mrUnDtBJlSbU2jNRfwsHryKh6Hil4K+FDMkZbGWCvvWBycqxKVsA4xu2Ajdu/+6wzchz x5ybZ3jILTaTDCnwq7061sPEvxXnm1hZ4e5sYIairacx7hQBm0xKMNc8Ipb5an5r1eTuq Mx39Rgz70X4hXTZh5wD2RHaGUm5ucEFTKRZRrKCJOh/jg+yGWKt4ug+CIhnN2GkAFEERR Ub1M4IZL4bxuhWEBMpovZBmJK3l3CKLxLcUvQr+mTIXa1HuwUGnSdIeZbdSymMlpEEWiU DGhIlLLdiFsi3Ob0U/76ExilsDQGqm1cSKXPJPgf19YE5iZDC4wkCycYINVKd6h7F/Q== 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=DxbRc9k3; 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 5F5F460A3803 for ; Thu, 22 Oct 2026 13:42:47 +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=DxbRc9k3 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 773861F000C3; Thu, 22 Oct 2026 13:42:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792676567; bh=s4AuCrYsn4dS2nLKpVvR0o43olVmPhMRKwWCMlr93FY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DxbRc9k3HUL3lTMaa5NWXt15ynEQ0jMHR7pVZVs/o+2254/iYkKL/qGhyF5Qdii83 WUDZpOdJWsb4iUl0S9YlCSe4isqgDVse4mBMhQQN//S/J1yS62wVo2j2h4zrzpAnH6 uuGbwKnO43VA4j8+YRzB7P/Nyd0uPscAKWNVS39cc7YjSByLRBnZqWF6GtV7VifI/r 4QHaVwa20f/dlRXw0dKFFjs7nleLF9+Ze3nHGc4+KKzX3JJwG3NUu5fPDUFr+mOCEH j78YwfUkDcRe5X4Bl0+TY63mSEW/03FteIPqJI8aES+VNVGwQN2vpAjwMwTbUbUVDA qKD9JnKUfZMjw== From: Sasha Levin To: stable@vger.kernel.org Cc: Donggeun Yoo , Steven Rostedt , Sasha Levin Subject: [PATCH 6.18.y 4/4] tracing: Fix NULL dereference when copying keys for a field variable Date: Thu, 22 Oct 2026 09:42:42 -0400 Message-ID: <20261022134230.1444063-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261022134230.1444063-1-sashal@kernel.org> References: <2026102122-spinster-handler-2d56@gregkh> <20261022134230.1444063-1-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 6e9400c62cd01..200373e19e383 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -3081,7 +3081,7 @@ 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