linux-kernel - [PATCH 3/3] dyndbg: fix problem parsing format="foo bar"

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Message-Id: <20200824185412.1617174-4-jim.cromie@gmail.com>
Date:   Mon, 24 Aug 2020 12:54:12 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org
Cc:     Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH 3/3] dyndbg: fix problem parsing format="foo bar"

 14775b049642 dyndbg: accept query terms like file=bar and module=foo

That commit broke on a tokenization modality where a word could start
with a quote, but couldnt continue with one.  So the above would
tokenize as 'format="foo' and 'bar"', and fail hard.

This commit fixes the tokenizer by terminating an unquoted token on
the '=', avoiding that problem.  And since ddebug-parse-query will
never see a combined 'keyword=value', revert those parts of the
previous commit.

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 lib/dynamic_debug.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index b6ab2c643116..4af686e6ef59 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -237,6 +237,7 @@ static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 {
 	int nwords = 0;
 
+	vpr_info("entry, buf:'%s'\n", buf);
 	while (*buf) {
 		char *end;
 
@@ -247,6 +248,8 @@ static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 		if (*buf == '#')
 			break;	/* token starts comment, skip rest of line */
 
+		vpr_info("start-of-word:%d '%s'\n", nwords, buf);
+
 		/* find `end' of word, whitespace separated or quoted */
 		if (*buf == '"' || *buf == '\'') {
 			int quote = *buf++;
@@ -257,7 +260,9 @@ static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 				return -EINVAL;	/* unclosed quote */
 			}
 		} else {
-			for (end = buf; *end && !isspace(*end); end++)
+			for (end = buf;
+			     *end && *end != '=' && !isspace(*end);
+			     end++)
 				;
 			BUG_ON(end == buf);
 		}
@@ -373,30 +378,20 @@ static int ddebug_parse_query(char *words[], int nwords,
 	unsigned int i;
 	int rc = 0;
 	char *fline;
-	char *keyword, *arg;
 
+	if (nwords % 2 != 0) {
+		pr_err("expecting pairs of match-spec <value>\n");
+		return -EINVAL;
+	}
 	if (modname)
 		/* support $modname.dyndbg=<multiple queries> */
 		query->module = modname;
 
-	for (i = 0; i < nwords; i++) {
-		/* accept keyword=arg */
-		vpr_info("%d w:%s\n", i, words[i]);
-
-		keyword = words[i];
-		arg = strchr(keyword, '=');
-		if (arg) {
-			*arg++ = '\0';
-		} else {
-			i++; /* next word is arg */
-			if (!(i < nwords)) {
-				pr_err("missing arg to keyword: %s\n", keyword);
-				return -EINVAL;
-			}
-			arg = words[i];
-		}
-		vpr_info("%d key:%s arg:%s\n", i, keyword, arg);
+	for (i = 0; i < nwords; i+=2) {
+		char *keyword = words[i];
+		char *arg = words[i+1];
 
+		vpr_info("key:'%s' arg:'%s'\n", keyword, arg);
 		if (!strcmp(keyword, "func")) {
 			rc = check_set(&query->function, arg, "func");
 		} else if (!strcmp(keyword, "file")) {
-- 
2.26.2