From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cstnet.cn (smtp21.cstnet.cn [159.226.251.21]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 881573F7867; Wed, 1 Apr 2026 11:22:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.21 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775042559; cv=none; b=evD6OsjpBsq1Zbd6kyFAeERHwjFP9bi5zaTVO3i0cw3QGICIn33+WtSL1UPV14cWgEeezuGIwTf9ZuGN+sVr2obKY7DZTHXxV50HhqiwnZ2gfQP6EJOK0/7+3cNA1VMKeEpaYJfmNnlyDbG86KBXofbHRavQsBJQN5AkfPP/z9o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775042559; c=relaxed/simple; bh=Bx+tCa9Cg0O972ijwfPaasWig6LowsOhqwwdri2zYUk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=mT8rBsZe2QKyluXh0cAOJDx0ObF2UskLpR0JtasYoJnkg1TabiD2iWiRKWWKCdmjMrVNS9Efq7HWVcfri8uMLmocDuFwofFglTe1QNHnn64wnfc/0UOsnQF+nyrHrqNwTybpNBryib8AO7m2MXewqZNuw90uv+xi4y90E3WDdkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from localhost.localdomain (unknown [111.196.245.197]) by APP-01 (Coremail) with SMTP id qwCowAA34m3y_8xpatzbCw--.6665S3; Wed, 01 Apr 2026 19:22:28 +0800 (CST) From: Pengpeng Hou To: rostedt@goodmis.org Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, tom.zanussi@linux.intel.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, pengpeng@iscas.ac.cn Subject: [PATCH v2 2/2] tracing/hist: reject synthetic-field strings that exceed MAX_FILTER_STR_VAL Date: Wed, 1 Apr 2026 19:22:24 +0800 Message-ID: <20260401112224.85582-2-pengpeng@iscas.ac.cn> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:qwCowAA34m3y_8xpatzbCw--.6665S3 X-Coremail-Antispam: 1UD129KBjvJXoWxZrWDJFW7AF1DAr4UAry3twb_yoWrurWxpr WYv3s8G3yUJr1Igr43C3WUCFyrCw4kuw1DG3Wa9ws5tr1Yyrs7KrWjkry8Xas5tryjvwsI gF4DXr98CwsruFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBm14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r1I6r4UM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1l84 ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1le2I2 62IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcV AFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG 0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lc7CjxVAaw2AFwI0_JF0_Jw1l42 xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWU GwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI4 8JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4U MIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I 8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUemhwUUUUU X-CM-SenderInfo: pshqw1xhqjqxpvfd2hldfou0/ The synthetic field helpers build a prefixed synthetic field name and a hist trigger command in fixed MAX_FILTER_STR_VAL staging buffers. Even when each individual field or filter string stays within that limit, the combined "keys=...:synthetic_...=... if ..." command can exceed 256 bytes and overrun the scratch buffer. Keep MAX_FILTER_STR_VAL as the tracing-side limit and reject synthetic field names or generated commands that do not fit in that bound before formatting them into the fixed buffers. Fixes: 02205a6752f2 ("tracing: Add support for 'field variables'") Signed-off-by: Pengpeng Hou --- Changes since v1: https://lore.kernel.org/all/20260329030950.32503-1-pengpeng@iscas.ac.cn/ - keep MAX_FILTER_STR_VAL as the fixed tracing-side limit - reject overlong synthetic names and generated commands with -E2BIG - drop the previous dynamic-allocation approach kernel/trace/trace_events_hist.c | 57 +++++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 16 deletions(-) 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); + 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) { -- 2.50.1 (Apple Git-155)