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smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id D80F78AB8F; Wed, 8 Apr 2026 21:30:03 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf08.hostedemail.com (Postfix) with ESMTPA id 18F9D2002B; Wed, 8 Apr 2026 21:30:02 +0000 (UTC) Date: Wed, 8 Apr 2026 17:31:18 -0400 From: Steven Rostedt To: Pengpeng Hou Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, tom.zanussi@linux.intel.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] tracing/hist: reject synthetic-field strings that exceed MAX_FILTER_STR_VAL Message-ID: <20260408173118.25aa80b8@gandalf.local.home> In-Reply-To: <20260401112224.85582-2-pengpeng@iscas.ac.cn> References: <20260401112224.85582-2-pengpeng@iscas.ac.cn> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 18F9D2002B X-Stat-Signature: kgf5i4xu64pfgzbprctj5awn6drw1y7p X-Rspamd-Server: rspamout03 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+EtflEPkF6Bl7iXtJq8ZU8gTJVTe2tCns= X-HE-Tag: 1775683802-823175 X-HE-Meta: U2FsdGVkX1/iNYvhWMncvMIWHMg+h7oQf33AShEWBGYSTchOXH4IuTMJ/gY5Gk0y2pAK04NE75avBN90PTBWZQ/A7/6BxEO0MB4qd5rnl5LWuUVbXe3kwUTedxJVHl2QJej+XzXleAhf10fxfYY9CsiltHLccqWSQRSnXLo4vNK4gETtAaukiz3+Og3TWamh4ZyKZB4TMEq8iQzcM0HHRd2vkHEXn/OM+dcxC1CmIAUqGr/oomeqPVvdo7UZCyncEmAMVlwi29PARfF4NKFgv6b87knD9zLKByhc1uJNmDnYkF7YOURwolbKNG353MJd On Wed, 1 Apr 2026 19:22:24 +0800 Pengpeng Hou wrote: > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > index f9c8a4f078ea..4172c91605af 100644 > --- a/kernel/trace/trace_events_hist.c > +++ b/kernel/trace/trace_events_hist.c > @@ -2966,12 +2966,16 @@ find_synthetic_field_var(struct hist_trigger_data *target_hist_data, > struct hist_field *event_var; > char *synthetic_name; > > + if ((sizeof("synthetic_") - 1) + strlen(field_name) >= > + MAX_FILTER_STR_VAL) > + return ERR_PTR(-E2BIG); > + > synthetic_name = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL); > if (!synthetic_name) > return ERR_PTR(-ENOMEM); > > - strcpy(synthetic_name, "synthetic_"); > - strcat(synthetic_name, field_name); > + scnprintf(synthetic_name, MAX_FILTER_STR_VAL, "synthetic_%s", > + field_name); > > event_var = find_event_var(target_hist_data, system, event_name, synthetic_name); > > @@ -3018,6 +3022,8 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data, > struct hist_field *event_var; > char *saved_filter; > char *cmd; > + size_t cmdlen; > + size_t off; > int ret; > > if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX) { > @@ -3048,13 +3054,36 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data, > /* See if a synthetic field variable has already been created */ > event_var = find_synthetic_field_var(target_hist_data, subsys_name, > event_name, field_name); > - if (!IS_ERR_OR_NULL(event_var)) > + if (IS_ERR(event_var)) > + return event_var; > + if (event_var) > return event_var; > > var_hist = kzalloc_obj(*var_hist); > if (!var_hist) > return ERR_PTR(-ENOMEM); > > + saved_filter = find_trigger_filter(hist_data, file); > + > + cmdlen = strlen("keys=") + strlen(":synthetic_") + > + strlen(field_name) + strlen("=") + strlen(field_name); Instead of doing all this complex updates, let's use seq_buf in this patch instead. That's what it's for. I'll take patch 1 as is, just update this patch. Thanks, -- Steve > + first = true; > + for_each_hist_key_field(i, hist_data) { > + key_field = hist_data->fields[i]; > + if (!first) > + cmdlen++; > + cmdlen += strlen(key_field->field->name); > + first = false; > + } > + > + if (saved_filter) > + cmdlen += strlen(" if ") + strlen(saved_filter); > + > + if (cmdlen >= MAX_FILTER_STR_VAL) { > + kfree(var_hist); > + return ERR_PTR(-E2BIG); > + } > + > cmd = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL); > if (!cmd) { > kfree(var_hist); > @@ -3062,28 +3091,24 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data, > } > > /* Use the same keys as the compatible histogram */ > - strcat(cmd, "keys="); > + off = scnprintf(cmd, MAX_FILTER_STR_VAL, "keys="); > + first = true; > > for_each_hist_key_field(i, hist_data) { > key_field = hist_data->fields[i]; > - if (!first) > - strcat(cmd, ","); > - strcat(cmd, key_field->field->name); > + off += scnprintf(cmd + off, MAX_FILTER_STR_VAL - off, "%s%s", > + first ? "" : ",", key_field->field->name); > first = false; > } > > /* Create the synthetic field variable specification */ > - strcat(cmd, ":synthetic_"); > - strcat(cmd, field_name); > - strcat(cmd, "="); > - strcat(cmd, field_name); > + off += scnprintf(cmd + off, MAX_FILTER_STR_VAL - off, > + ":synthetic_%s=%s", field_name, field_name); > > /* Use the same filter as the compatible histogram */ > - saved_filter = find_trigger_filter(hist_data, file); > - if (saved_filter) { > - strcat(cmd, " if "); > - strcat(cmd, saved_filter); > - } > + if (saved_filter) > + scnprintf(cmd + off, MAX_FILTER_STR_VAL - off, " if %s", > + saved_filter); > > var_hist->cmd = kstrdup(cmd, GFP_KERNEL); > if (!var_hist->cmd) {