From: John Ogness <john.ogness@linutronix.de>
Date: Sun, 24 Jan 2021 20:27:28 +0000 (+0106)
Subject: printk: fix string termination for record_print_text()
X-Git-Tag: rel_imx_5.10.35_2.0.0-somdevices.0~363^2~2060
X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=d5ac8304e18025a522b5d1d87629e926064ce134;p=linux.git

printk: fix string termination for record_print_text()

commit 08d60e5999540110576e7c1346d486220751b7f9 upstream.

Commit f0e386ee0c0b ("printk: fix buffer overflow potential for
print_text()") added string termination in record_print_text().
However it used the wrong base pointer for adding the terminator.
This led to a 0-byte being written somewhere beyond the buffer.

Use the correct base pointer when adding the terminator.

Fixes: f0e386ee0c0b ("printk: fix buffer overflow potential for print_text()")
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210124202728.4718-1-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 807810216492..aafec8cb8637 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1445,7 +1445,7 @@ static size_t record_print_text(struct printk_record *r, bool syslog,
 	 * not counted in the return value.
 	 */
 	if (buf_size > 0)
-		text[len] = 0;
+		r->text_buf[len] = 0;
 
 	return len;
 }