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[15.164.162.188]) by smtp.gmail.com with ESMTPSA id d5-20020a170902cec500b0016a4db1342esm3026608plg.193.2022.06.23.03.35.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jun 2022 03:35:57 -0700 (PDT) From: YongSu Yoo To: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, mchehab@kernel.org, hps@selasky.org, kieran.bingham@ideasonboard.com Cc: YongSu Yoo Subject: [PATCH] media: dvb_ringbuffer : Fix a bug in dvb_ringbuffer.c Date: Thu, 23 Jun 2022 10:35:43 +0000 Message-Id: <20220623103543.4138-1-yongsuyoo0215@gmail.com> X-Mailer: git-send-email 2.17.1 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -2.5 (--) X-LSpam-Report: No, score=-2.5 required=5.0 tests=BAYES_00=-1.9,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,FREEMAIL_FORGED_FROMDOMAIN=0.001,FREEMAIL_FROM=0.001,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1 autolearn=ham autolearn_force=no Signed-off-by:Yongsu Yoo 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. --- 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) {