[PATCH] kmsg: escape the backslash character while exporting data

[Kay Sievers <kay@vrfy.org>]

From: Kay Sievers <kay@vrfy.org>
Subject: kmsg: escape the backslash character while exporting data

Non-printable characters in the log data are hex-escaped to ensure safe
post processing. We need to escape a backslash we find in the data, to be
able to distinguish it from a backslash we add for the escaping.

Also escape the non-printable character 127.

Thanks to Miloslav Trmac for the heads up.

Signed-off-by: Kay Sievers <kay@vrfy.org>
---
 kernel/printk.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -465,7 +465,7 @@ static ssize_t devkmsg_read(struct file
 	for (i = 0; i < msg->text_len; i++) {
 		unsigned char c = log_text(msg)[i];
 
-		if (c < ' ' || c >= 128)
+		if (c < ' ' || c >= 127 || c == '\\')
 			len += sprintf(user->buf + len, "\\x%02x", c);
 		else
 			user->buf[len++] = c;
@@ -489,7 +489,7 @@ static ssize_t devkmsg_read(struct file
 				continue;
 			}
 
-			if (c < ' ' || c >= 128) {
+			if (c < ' ' || c >= 127 || c == '\\') {
 				len += sprintf(user->buf + len, "\\x%02x", c);
 				continue;
 			}