From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBEEE4AEBF5; Fri, 11 Sep 2026 18:16:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789150580; cv=none; b=fJBAfGlk1fw7AAuFvEWKMKY1yVEPldkuiQK6Dw0ScEdTdhD+1Pgtc+7mE9IImDoOrjCIZyFl/ShTz1REIIP4fcU/6POCSeQtIjVRnkPASBAGAujiW8ysz4Eu1VP68fs8Dxku16VfbFMdOLwfbrpWjXqsmzHgj61pA5mQ4ULDRig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789150580; c=relaxed/simple; bh=QSD3eMCLrLuQgTXh7gAKcKxBIwLo7qPxGf2rRAEPZEU=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=JhZWqJktRH0JVHs820j3LXFgzFuHwmhjJwenO237pIvFB0/4TO7weRi73iaux93b0PN7D4DSVgPChuO3uPNeGy6UgQ+ZtE5CC9r1FZqEvr98WmF7kw4To1RIi0+q1E35PB4gcPC5sLk9PRTrWF6HS5bm1d09sGRQpi87PMyhCg8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=h3IUTb76; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="h3IUTb76" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3105B1F0089C; Fri, 11 Sep 2026 18:16:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789150568; bh=bL/rSYTIGCPz2ML0qUfMnK6Kt8ZSclOopkEza4Oddx4=; h=Date:From:To:Cc:Subject:References; b=h3IUTb76WsZKGoO96+ZL26cjzLbvlgRpKICsFfxBuC346VMm7qBdNfDQQLk/giFKW AjSHpinvkDzHwWOAV6n+mvwNYl74tDrXbIScd32Z/od7RHI4O14JbfYHI+o2YXfrcc uPpK4r12aQqE3c4L9U10cOY3w0TbMd2uWXoM68FpI27Ae/zAJkEd346WECBqdMtsOz V4Dzpk4HO5qJFiAJvKw+cSYz4u4VK1KXjjaj6p4yXs/Pm2jTG+T7X5+DkT8HtEcDxu LvQx84EoycGvgnJDKiR/6x8336TQzbBUlv0m89C+dsIT8LnFCjAaxPLQz4fO3rl972 D8h4B8Wzoz5+A== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1x55oX-000000094yM-3NFq; Fri, 11 Sep 2026 14:17:29 -0400 Message-ID: <20260911181729.623284631@kernel.org> User-Agent: quilt/0.69 Date: Fri, 11 Sep 2026 14:16:43 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, Donggeun Yoo Subject: [for-linus][PATCH 07/20] tracing: Free histogram the field rejected for a bad modifier References: <20260911181636.485043797@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Donggeun Yoo Writing a hist trigger whose value or variable carries a modifier that is not allowed there leaks the fields that were built for it. __create_val_field() takes the field from parse_expr() and stores it in hist_data->fields[] only after the modifier checks have run: hist_field = parse_expr(hist_data, file, field_str, flags, var_name, &n_subexprs); ... if (hist_field->flags & HIST_FIELD_FL_VAR) { if (hist_field->flags & (...)) goto err; } else { if (hist_field->flags & (...)) goto err; } hist_data->fields[val_idx] = hist_field; Both checks jump past that store, and the err label returns without freeing anything. The error unwinds to create_hist_data(), which calls destroy_hist_data() -> destroy_hist_fields(), and that reaches a field only by walking fields[]. A field that never got there is unreachable. commit e0213434fe3e ("tracing: Do not let histogram values have some modifiers") set ret to -EINVAL and fell through to the store, which left the field owned by fields[] and freed along with the rest of hist_data. Splitting the check into a value case and a variable case replaced that fall-through with a goto that skips it. With CONFIG_DEBUG_KMEMLEAK, 200 writes of # echo 'hist:keys=prev_pid:vals=next_pid.log2' > \ events/sched/sched_switch/trigger each correctly rejected with -EINVAL, leave 332 unreferenced objects (63744 bytes) reported at create_hist_field(); 200 install and remove cycles of a valid trigger leave none. A '.log2' field is two allocations, since create_hist_field() puts the plain field in operands[0] of the log2 field, and both are reported. Use destroy_hist_field() rather than __destroy_hist_field() so that operands[0] is freed as well. It returns early for HIST_FIELD_FL_VAR_REF, which is what an operand owned by hist_data->var_refs[] needs; the rejected field itself is never a var ref, because a var ref never carries a modifier flag. Cc: stable@vger.kernel.org Fixes: e30fbc618e97 ("tracing/histograms: Allow variables to have some modifiers") Link: https://patch.msgid.link/20260907034948.240387-1-donggeunyoo.kernel@gmail.com Signed-off-by: Donggeun Yoo Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_hist.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index bbdd56208eff..8cad99a8d01e 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -4317,6 +4317,7 @@ static int __create_val_field(struct hist_trigger_data *hist_data, return ret; err: hist_err(file->tr, HIST_ERR_BAD_FIELD_MODIFIER, errpos(field_str)); + destroy_hist_field(hist_field, 0); return -EINVAL; } -- 2.53.0