* [PATCH] printk: fix string termination for record_print_text()
@ 2021-01-24 20:27 John Ogness
2021-01-25 10:55 ` Petr Mladek
0 siblings, 1 reply; 2+ messages in thread
From: John Ogness @ 2021-01-24 20:27 UTC (permalink / raw)
To: Petr Mladek
Cc: Sergey Senozhatsky, Sergey Senozhatsky, Steven Rostedt,
Linus Torvalds, Sven Schnelle, linux-kernel
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>
---
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] printk: fix string termination for record_print_text()
2021-01-24 20:27 [PATCH] printk: fix string termination for record_print_text() John Ogness
@ 2021-01-25 10:55 ` Petr Mladek
0 siblings, 0 replies; 2+ messages in thread
From: Petr Mladek @ 2021-01-25 10:55 UTC (permalink / raw)
To: John Ogness
Cc: Sergey Senozhatsky, Sergey Senozhatsky, Steven Rostedt,
Linus Torvalds, Sven Schnelle, linux-kernel
On Sun 2021-01-24 21:33:28, John Ogness wrote:
> 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>
The patch is pushed in kernel/printk.git, branch printk-rework.
I am going to send pull request for-5.11 later today.
Thanks a lot for the debugging and quick fix. I feel shame that
I did not caught this during the review.
Best Regards,
Petr
^ permalink raw reply [flat|nested] 2+ messages in thread
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