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=1793209700; b=g3UaIeFQJ1f+U5iuCC2+XIRHyA4mAqx0WTcuG/5+b30R9S/MwJ3gjz4LdSe7u4wngaHy YyLZPBPck4ePg+VmH3gG1xjccP5W8vrycDqISBIggu8Jnqmux5UnK1KuBbFZl7NbFy9Sq wj0RZ19vGlmilgBPz/l3BumRbjmNM7zn9C2i9WS2o5qFI6D+0eN462RXV12mHqxk+6+la 31YFXjTHe9pygagxUgheCAe0Gexdtj8KlAB7R6Stx2Ae4ZUgU4xx0hJwme8BqGiTvS60c 5DG9VHTf7FYub8bNNu5PnJrTBz4WbrUM43F5pTgscRzetreg+eUJd4a5mpsrDmwjnig== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793209700; 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=jp72a3uWd+NXWHBxhuiatawKxDA66pQA9DS99TvERdk=; b=lkq4YFoAlEfzBnE2SBmRs8TW3anvmy5fx0Tn7IIn6gsFTP37bx9JLD4thkmH4tMLhjzX sF/C8ONKv7Y6IrYT3GS76iiUv6Tcs5vXr7qucbQRF4puC8Hyh0805VOGmkQaBQ4Sp+m7i EQCvO2PZvP0VRT0PF3m95E4yVhCa+86tvCm8g8iRUSpuFvSU7rgEZe02alPEctQcUQPna OMcnzUhpDoyhVvixnt+j2HndTT3Vo4xZzeQ9gP9hqw+4tpGz7N2gsmFJPF4L5T3NZ+iq9 Pa2cSs99qiKmYK6bMzBjYRAmi07IMuAXERLfOt1qoQBeePm1uCatjZMOqoka6B8MAIA== 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=DzKzE0Op; 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 B265B606A31D; Wed, 28 Oct 2026 17:48:19 +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=DzKzE0Op Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F46A1F01825; Wed, 28 Oct 2026 17:48:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793209699; bh=jp72a3uWd+NXWHBxhuiatawKxDA66pQA9DS99TvERdk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DzKzE0OpeQnzWi+ICzzGRdUpsDG2Cxdqn9twiVjDYJlzRMexlAEGFOvGSrYlxSJmn 8tFGd9+0g33HO+5qL3XVSc2Nb+A8SQ7fmAQMen2PlZjqHwWY1SB9rF30gdUGNwNsNj BAu9zV7UxRZ0cXObBbTI7AZANrJfVOCeKP9yIHgc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, sashiko-bot@kernel.org, Donggeun Yoo , Steven Rostedt Subject: [PATCH 6.18 039/109] tracing: Unregister field variable histograms when the command fails Date: Wed, 28 Oct 2026 18:00:23 +0100 Message-ID: <20261028165943.281433012@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165942.357251485@linuxfoundation.org> References: <20261028165942.357251485@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Donggeun Yoo commit 91c14d6c13096091c56304120aaa26e479130b8b upstream. An action that names a field on another event needs that field as a variable, so create_field_var_hist() registers a second hist trigger on that event to provide it, and records it in target_hist_data->field_var_hists[]. If a later part of the same command fails, create_actions() returns an error and event_hist_trigger_parse() jumps to out_free. The write fails with -EINVAL and sched_switch gets no trigger, but: # echo 'hist:keys=pid:ts0=common_timestamp.usecs' >> \ events/sched/sched_waking/trigger # echo 'my_synth u64 lat; int a; int b' >> synthetic_events # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:\ onmatch(sched.sched_waking).my_synth($wakeup_lat,prio,nosuchfld)'\ >> events/sched/sched_switch/trigger # cat events/sched/sched_waking/trigger hist:keys=pid:vals=hitcount:ts0=common_timestamp.usecs:sort=hitcount:size=2048:clock=global [active] hist:keys=pid:vals=hitcount:synthetic_prio=prio:sort=hitcount:size=2048 [active] The second histogram is the one created for 'prio'. It is still active and still counting. out_free reaches destroy_field_var_hists(), which frees the field_var_hists[] entries, but never unregister_field_var_hists(), which is what removes the triggers and runs only from event_hist_trigger_free(). The entry is freed and the trigger is left with nothing tracking it. Unregister the field variable histograms in out_free as well, and record each one as soon as its trigger is registered rather than after the lookup that follows it, so no exit can leave a registered trigger untracked. The entry then belongs to field_var_hists[] and is released by destroy_field_var_hists(), so freeing it on that exit would be a double free. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260914104036.1768529-1-donggeunyoo.kernel@gmail.com Fixes: 02205a6752f2 ("tracing: Add support for 'field variables'") Reported-by: sashiko-bot@kernel.org Closes: https://lore.kernel.org/all/20260913204302.DB2551F000FF@smtp.kernel.org/ Signed-off-by: Donggeun Yoo Assisted-by: Claude:claude-fable-5 Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_events_hist.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -3114,20 +3114,18 @@ create_field_var_hist(struct hist_trigge kfree(cmd); + n = target_hist_data->n_field_var_hists; + target_hist_data->field_var_hists[n] = var_hist; + target_hist_data->n_field_var_hists++; + /* If we can't find the variable, something went wrong */ event_var = find_synthetic_field_var(target_hist_data, subsys_name, event_name, field_name); if (IS_ERR_OR_NULL(event_var)) { - kfree(var_hist->cmd); - kfree(var_hist); hist_err(tr, HIST_ERR_SYNTH_VAR_NOT_FOUND, errpos(field_name)); return ERR_PTR(-EINVAL); } - n = target_hist_data->n_field_var_hists; - target_hist_data->field_var_hists[n] = var_hist; - target_hist_data->n_field_var_hists++; - return event_var; } @@ -6943,6 +6941,8 @@ static int event_hist_trigger_parse(stru trigger_data_free(trigger_data); + unregister_field_var_hists(hist_data); + destroy_hist_data(hist_data); goto out; }