From 668af87f995b6d6d09595c088ad1fb5dd9ff25d2 Mon Sep 17 00:00:00 2001 From: John Ogness Date: Wed, 13 Jan 2021 15:48:34 +0106 Subject: [PATCH] printk: ringbuffer: fix line counting Counting text lines in a record simply involves counting the number of newline characters (+1). However, it is searching the full data block for newline characters, even though the text data can be (and often is) a subset of that area. Since the extra area in the data block was never initialized, the result is that extra newlines may be seen and counted. Restrict newline searching to the text data length. Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer") Signed-off-by: John Ogness Reviewed-by: Petr Mladek Acked-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20210113144234.6545-1-john.ogness@linutronix.de --- 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 74e25a1..617dd63 100644 --- a/kernel/printk/printk_ringbuffer.c +++ b/kernel/printk/printk_ringbuffer.c @@ -1720,7 +1720,7 @@ static bool copy_data(struct prb_data_ring *data_ring, /* Caller interested in the line count? */ if (line_count) - *line_count = count_lines(data, data_size); + *line_count = count_lines(data, len); /* Caller interested in the data content? */ if (!buf || !buf_size) -- 2.7.4