[PATCH] printk: fix string termination for record_print_text()

From: John Ogness
Date: Sun Jan 24 2021 - 15:36:07 EST


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@xxxxxxxxxxxxx>
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
---
kernel/printk/printk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6639a0cfe0ac..5a95c688621f 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1398,7 +1398,7 @@ 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;
}
--
2.20.1