From bbffe6f6b933198260db6e2dcd78f7de3e6b5aa6 Mon Sep 17 00:00:00 2001 From: YongSu Yoo Date: Thu, 23 Jun 2022 11:35:43 +0100 Subject: [PATCH] media: dvb_ringbuffer : Fix a bug in dvb_ringbuffer.c The function dvb_ringbuffer_pkt_next in /linux-next/drviers/media/dvb-core/dvb_ringbuffer.c, which searches the idx of the next valid packet in the ring buffer of the ca->slot_info[slot].rx_buffer at /linux-next/drivers/media/dvb-core/dvb_ca_en50221.c, has the following problem. In calculating the amounts of the consumed address of the ring buffer, if the read address(rbuf->pread) of the ring buffer is smaller than the idx, the amounts of the searched address should be (idx - rbuf->pread), whereas if the read address(rbuf->pread) of the ring buffer is larger than the idx, the amounts of the consumed address should be (idx - rbuf->pread + rbug->size). But there exists an incorrect logic that the rbug-size was not properly added on (idx - rbug->pread) in the later case. With this commit, we fixed this bug. Link: https://lore.kernel.org/linux-media/20220623103543.4138-1-yongsuyoo0215@gmail.com Signed-off-by: Yongsu Yoo Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-core/dvb_ringbuffer.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-core/dvb_ringbuffer.c b/drivers/media/dvb-core/dvb_ringbuffer.c index d1d471af0636..7d4558de8e83 100644 --- a/drivers/media/dvb-core/dvb_ringbuffer.c +++ b/drivers/media/dvb-core/dvb_ringbuffer.c @@ -335,7 +335,9 @@ ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size; } - consumed = (idx - rbuf->pread) % rbuf->size; + consumed = (idx - rbuf->pread); + if (consumed < 0) + consumed += rbuf->size; while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) { -- 2.11.0