[linux-dvb] Re: CRC32 errors in sections

[Holger Waechtler <holger@convergence.de>]

Jeremy Hall wrote:
> In the new year, Holger Waechtler wrote:
>
> > Jeremy Hall wrote:
> > The DMX_CHECK_CRC flag is not implemented for av7110 based cards right 
> > now. If you want to implement this follow the Budget codepath for an 
> > example.
> Where does that codepath start? Why has it not been implemented?
in the interrupt handlers. vpeirq() and fidbirq() for budget cards and 
debiirq() for av7110 based cards.


> > > When the driver gives you a section, does it at least 
> > > sanity check the seclen to determine if it will make a memory out of 
> > > bounds problem so it won't happily overwrite other memory?
> > The read() function call will never read more bytes than you specified 
> > in the argument, so you'll never overwrite more memory than you passed 
> > as read()-buffer.
> Is it a mmap'd read and you're actually accessing the incoming buffer, or 
> does the driver copy a section to you? This question relates to the driver 
> copying that data to userspace--how does it know how much to copy.  If the 
> seclen is not correct, can the driver trash its memory structures?
no. If this happens you definitely found a driver bug.

Holger



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