linux-kernel - [PATCH v2 6/7] tracing: Handle synthetic event array field type checking correctly

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 12 Oct 2020 15:18:08 -0500
From:   Tom Zanussi <zanussi@...nel.org>
To:     rostedt@...dmis.org, axelrasmussen@...gle.com
Cc:     mhiramat@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 6/7] tracing: Handle synthetic event array field type checking correctly

Since synthetic event array types are derived from the field name,
there may be a semicolon at the end of the type which should be
stripped off.

If there are more characters following that, normal type string
checking will result in an invalid type.

Without this patch, you can end up with an invalid field type string
that gets displayed in both the synthetic event description and the
event format:

Before:

  # echo 'myevent char str[16]; int v' >> synthetic_events
  # cat synthetic_events
    myevent	char[16]; str; int v

  name: myevent
  ID: 1936
  format:
  	field:unsigned short common_type;	offset:0;	size:2;	signed:0;
  	field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
  	field:unsigned char common_preempt_count;	offset:3;	size:1;	signed:0;
  	field:int common_pid;	offset:4;	size:4;	signed:1;

  	field:char str[16];;	offset:8;	size:16;	signed:1;
  	field:int v;	offset:40;	size:4;	signed:1;

  print fmt: "str=%s, v=%d", REC->str, REC->v

After:

  # echo 'myevent char str[16]; int v' >> synthetic_events
  # cat synthetic_events
    myevent	char[16] str; int v

  # cat events/synthetic/myevent/format
  name: myevent
  ID: 1936
  format:
	field:unsigned short common_type;	offset:0;	size:2;	signed:0;
	field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
	field:unsigned char common_preempt_count;	offset:3;	size:1;	signed:0;
	field:int common_pid;	offset:4;	size:4;	signed:1;

	field:char str[16];	offset:8;	size:16;	signed:1;
	field:int v;	offset:40;	size:4;	signed:1;

  print fmt: "str=%s, v=%d", REC->str, REC->v

Fixes: 4b147936fa50 (tracing: Add support for 'synthetic' events)
Reported-by: Masami Hiramatsu <mhiramat@...nel.org>
Signed-off-by: Tom Zanussi <zanussi@...nel.org>
---
 kernel/trace/trace_events_synth.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 64c65be62dfe..5c3f5ae6f0bd 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -179,7 +179,7 @@ static int synth_field_string_size(char *type)
 	start += sizeof("char[") - 1;
 
 	end = strchr(type, ']');
-	if (!end || end < start)
+	if (!end || end < start || type + strlen(type) > end + 1)
 		return -EINVAL;
 
 	len = end - start;
@@ -630,8 +630,11 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
 	if (field_type[0] == ';')
 		field_type++;
 	len = strlen(field_type) + 1;
-	if (array)
+	if (array) {
 		len += strlen(array);
+		if (array[strlen(array) - 1] == ';')
+			len--;
+	}
 	if (prefix)
 		len += strlen(prefix);
 
-- 
2.17.1