[linux-dvb] [PATCH] 1/3: BUG FIX in dvb_ringbuffer_flush

From: Andrea <mariofutire@googlemail.com>
To: linux-dvb@linuxtv.org
Subject: [linux-dvb] [PATCH] 1/3: BUG FIX in dvb_ringbuffer_flush
Date: Sat, 22 Mar 2008 00:22:06 +0000	[thread overview]
Message-ID: <47E4512E.5000602@googlemail.com> (raw)

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I've been playing with DMX_SET_BUFFER_SIZE and I've had a problem when I tried to resize the buffer
to a smaller size.

dvb_dmxdev_set_buffer_size flushes the ringbuffer and then replaces it with a new one.
What happens if the current pointer is on a position that would be invalid in the new buffer? An
access violation.

This because dvb_ringbuffer_flush resets the 2 pointers to the vaule of pwrite (which could be after
the end of the new buffer).
I think it is safer to reset them to 0.

Andrea


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diff -r 1886a5ea2f84 linux/drivers/media/dvb/dvb-core/dvb_ringbuffer.c

--- a/linux/drivers/media/dvb/dvb-core/dvb_ringbuffer.c	Fri Mar 21 08:04:55 2008 -0300
+++ b/linux/drivers/media/dvb/dvb-core/dvb_ringbuffer.c	Sat Mar 22 00:07:53 2008 +0000
@@ -86,7 +86,7 @@ ssize_t dvb_ringbuffer_avail(struct dvb_
 
 void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
 {
-	rbuf->pread = rbuf->pwrite;
+	rbuf->pread = rbuf->pwrite = 0;
 	rbuf->error = 0;
 }
 


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