From nobody Thu Sep 11 20:36:23 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD0BEC61DA4 for ; Fri, 17 Feb 2023 00:51:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229490AbjBQAvD (ORCPT ); Thu, 16 Feb 2023 19:51:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230157AbjBQAu6 (ORCPT ); Thu, 16 Feb 2023 19:50:58 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9E4C5775C for ; Thu, 16 Feb 2023 16:50:42 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 2F4B0B82ABC for ; Fri, 17 Feb 2023 00:50:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6733C433EF; Fri, 17 Feb 2023 00:50:39 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1pSoxS-000qMe-24; Thu, 16 Feb 2023 19:50:38 -0500 Message-ID: <20230217005038.455296375@goodmis.org> User-Agent: quilt/0.66 Date: Thu, 16 Feb 2023 19:49:55 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , Tom Zanussi Subject: [for-next][PATCH 1/5] tracing/histogram: Dont use strlen to find length of stacktrace variables References: <20230217004954.719324747@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Tom Zanussi Because stacktraces are saved in dynamic strings, trace_event_raw_event_synth() uses strlen to determine the length of the stack. Stacktraces may contain 0-bytes, though, in the saved addresses, so the length found and passed to reserve() will be too small. Fix this by using the first unsigned long in the stack variables to store the actual number of elements in the stack and have trace_event_raw_event_synth() use that to determine the length of the stack. Link: https://lkml.kernel.org/r/1ed6906cd9d6477ef2bd8e63c61de20a9ffe64d7.16= 76063532.git.zanussi@kernel.org Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_hist.c | 12 ++++++++---- kernel/trace/trace_events_synth.c | 7 ++++++- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_h= ist.c index 7f3e6ca6f0fa..f21e42ddba69 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -3137,13 +3137,15 @@ static inline void __update_field_vars(struct traci= ng_map_elt *elt, size =3D min(val->size, STR_VAR_LEN_MAX); strscpy(str, val_str, size); } else { + char *stack_start =3D str + sizeof(unsigned long); int e; =20 - e =3D stack_trace_save((void *)str, + e =3D stack_trace_save((void *)stack_start, HIST_STACKTRACE_DEPTH, HIST_STACKTRACE_SKIP); if (e < HIST_STACKTRACE_DEPTH - 1) - ((unsigned long *)str)[e] =3D 0; + ((unsigned long *)stack_start)[e] =3D 0; + *((unsigned long *)str) =3D e; } var_val =3D (u64)(uintptr_t)str; } @@ -5135,13 +5137,15 @@ static void hist_trigger_elt_update(struct hist_tri= gger_data *hist_data, size =3D min(hist_field->size, STR_VAR_LEN_MAX); strscpy(str, val_str, size); } else { + char *stack_start =3D str + sizeof(unsigned long); int e; =20 - e =3D stack_trace_save((void *)str, + e =3D stack_trace_save((void *)stack_start, HIST_STACKTRACE_DEPTH, HIST_STACKTRACE_SKIP); if (e < HIST_STACKTRACE_DEPTH - 1) - ((unsigned long *)str)[e] =3D 0; + ((unsigned long *)stack_start)[e] =3D 0; + *((unsigned long *)str) =3D e; } hist_val =3D (u64)(uintptr_t)str; } diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_= synth.c index 306c89e0ce55..70bddb25d9c0 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -538,7 +538,12 @@ static notrace void trace_event_raw_event_synth(void *= __data, val_idx =3D var_ref_idx[field_pos]; str_val =3D (char *)(long)var_ref_vals[val_idx]; =20 - len =3D kern_fetch_store_strlen((unsigned long)str_val); + if (event->dynamic_fields[i]->is_stack) { + len =3D *((unsigned long *)str_val); + len *=3D sizeof(unsigned long); + } else { + len =3D kern_fetch_store_strlen((unsigned long)str_val); + } =20 fields_size +=3D len; } --=20 2.39.1