Re: [PATCH] printk: ringbuffer: Wrong data pointer when appending small string

From: Sergey Senozhatsky
Date: Thu Oct 15 2020 - 02:31:44 EST


On (20/10/14 19:50), Petr Mladek wrote:
> diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c
> index 2493348a1631..24a960a89aa8 100644
> --- a/kernel/printk/printk_ringbuffer.c
> +++ b/kernel/printk/printk_ringbuffer.c
> @@ -1125,7 +1125,10 @@ static char *data_realloc(struct printk_ringbuffer *rb,
>
> /* If the data block does not increase, there is nothing to do. */
> if (head_lpos - next_lpos < DATA_SIZE(data_ring)) {
> - blk = to_block(data_ring, blk_lpos->begin);
> + if (wrapped)
> + blk = to_block(data_ring, 0);
> + else
> + blk = to_block(data_ring, blk_lpos->begin);
> return &blk->data[0];
> }

Great catch.

Acked-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>

-ss