[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-Id: <20230811054528.never.165-kees@kernel.org>
Date: Thu, 10 Aug 2023 22:45:32 -0700
From: Kees Cook <keescook@...omium.org>
To: Petr Mladek <pmladek@...e.com>
Cc: Kees Cook <keescook@...omium.org>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Steven Rostedt <rostedt@...dmis.org>,
John Ogness <john.ogness@...utronix.de>,
Vijay Balakrishna <vijayb@...ux.microsoft.com>,
stable@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
"Guilherme G. Piccoli" <gpiccoli@...lia.com>,
"Paul E. McKenney" <paulmck@...nel.org>,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] printk: ringbuffer: Fix truncating buffer size min_t cast
If an output buffer size exceeded U16_MAX, the min_t(u16, ...) cast in
copy_data() was causing writes to truncate. This manifested as output
bytes being skipped, seen as %NUL bytes in pstore dumps when the available
record size was larger than 65536. Fix the cast to no longer truncate
the calculation.
Cc: Petr Mladek <pmladek@...e.com>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: John Ogness <john.ogness@...utronix.de>
Reported-by: Vijay Balakrishna <vijayb@...ux.microsoft.com>
Closes: https://lore.kernel.org/lkml/d8bb1ec7-a4c5-43a2-9de0-9643a70b899f@linux.microsoft.com/
Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer")
Cc: stable@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
kernel/printk/printk_ringbuffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c
index 2dc4d5a1f1ff..fde338606ce8 100644
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -1735,7 +1735,7 @@ static bool copy_data(struct prb_data_ring *data_ring,
if (!buf || !buf_size)
return true;
- data_size = min_t(u16, buf_size, len);
+ data_size = min_t(unsigned int, buf_size, len);
memcpy(&buf[0], data, data_size); /* LMM(copy_data:A) */
return true;
--
2.34.1
Powered by blists - more mailing lists