From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: Wed, 25 Apr 2018 09:50:49 +0000 (+0200)
Subject: Revert "kmsg: allow binary characters"
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1a05d276a899fd5c2616a3d4a9332b59a5f8d209;p=platform%2Fkernel%2Flinux-exynos.git

Revert "kmsg: allow binary characters"

This reverts commit bae6b52d8704da7e487c26c8f0e40491fe7792da.
---

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 20ebf827e858..d6b96136deb4 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -989,19 +989,15 @@ static ssize_t kmsg_read(struct log_buffer *log_b, struct file *file,
 		       user->seq, ts_usec, cont);
 	user->prev = msg->flags;
 
+	/* escape non-printable characters */
 	for (i = 0; i < msg->text_len; i++) {
 		unsigned char c = log_text(msg)[i];
 
-		append_char(&p, e, c);
+		if (c < ' ' || c >= 127 || c == '\\')
+			p += scnprintf(p, e - p, "\\x%02x", c);
+		else
+			append_char(&p, e, c);
 	}
-
-	/*
-	 * The \0 is delimits the text part, while the newline is for formatting
-	 * when catting the device directly. We cannot use \n for delimiting due
-	 * to security: else one could forge dictionary tags through the message
-	 * such as "text\n _PID=123"
-	 */
-	append_char(&p, e, '\0');
 	append_char(&p, e, '\n');
 
 	if (msg->dict_len) {
@@ -1021,6 +1017,11 @@ static ssize_t kmsg_read(struct log_buffer *log_b, struct file *file,
 				continue;
 			}
 
+			if (c < ' ' || c >= 127 || c == '\\') {
+				p += scnprintf(p, e - p, "\\x%02x", c);
+				continue;
+			}
+
 			append_char(&p, e, c);
 		}
 		append_char(&p, e, '\n');