linux-kernel - [PATCH v2 1/4] proc/bootconfig: Fix to use correct quotes for value

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Date:   Tue, 16 Jun 2020 19:14:08 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     stable@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 1/4] proc/bootconfig: Fix to use correct quotes for value

Fix /proc/bootconfig to select double or single quotes
corrctly according to the value.

If a bootconfig value includes a double quote character,
we must use single-quotes to quote that value.

This modifies if() condition and blocks for avoiding
double-quote in value check in 2 places. Anyway, since
xbc_array_for_each_value() can handle the array which
has a single node correctly.
Thus,

if (vnode && xbc_node_is_array(vnode)) {
	xbc_array_for_each_value(vnode)	/* vnode->next != NULL */
		...
} else {
	snprintf(val); /* val is an empty string if !vnode */
}

is equivalent to

if (vnode) {
	xbc_array_for_each_value(vnode)	/* vnode->next can be NULL */
		...
} else {
	snprintf("");	/* value is always empty */
}

Fixes: c1a3c36017d4 ("proc: bootconfig: Add /proc/bootconfig to show boot config list")
Cc: stable@...r.kernel.org
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 Changes in v2:
  - Sort local vars definition as upside-down xmas tree format.
  - Fix patch description (typo and add comments)
---
 fs/proc/bootconfig.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/proc/bootconfig.c b/fs/proc/bootconfig.c
index 9955d75c0585..ad31ec4ad627 100644
--- a/fs/proc/bootconfig.c
+++ b/fs/proc/bootconfig.c
@@ -26,8 +26,9 @@ static int boot_config_proc_show(struct seq_file *m, void *v)
 static int __init copy_xbc_key_value_list(char *dst, size_t size)
 {
 	struct xbc_node *leaf, *vnode;
-	const char *val;
 	char *key, *end = dst + size;
+	const char *val;
+	char q;
 	int ret = 0;
 
 	key = kzalloc(XBC_KEYLEN_MAX, GFP_KERNEL);
@@ -41,16 +42,20 @@ static int __init copy_xbc_key_value_list(char *dst, size_t size)
 			break;
 		dst += ret;
 		vnode = xbc_node_get_child(leaf);
-		if (vnode && xbc_node_is_array(vnode)) {
+		if (vnode) {
 			xbc_array_for_each_value(vnode, val) {
-				ret = snprintf(dst, rest(dst, end), "\"%s\"%s",
-					val, vnode->next ? ", " : "\n");
+				if (strchr(val, '"'))
+					q = '\'';
+				else
+					q = '"';
+				ret = snprintf(dst, rest(dst, end), "%c%s%c%s",
+					q, val, q, vnode->next ? ", " : "\n");
 				if (ret < 0)
 					goto out;
 				dst += ret;
 			}
 		} else {
-			ret = snprintf(dst, rest(dst, end), "\"%s\"\n", val);
+			ret = snprintf(dst, rest(dst, end), "\"\"\n");
 			if (ret < 0)
 				break;
 			dst += ret;