On Sun, May 14, 2006 at 06:24:09PM +0400, Alexey Dobriyan wrote:
> On Sun, May 14, 2006 at 04:20:52AM +0200, Jesper Juhl wrote:
> > First testing if a pointer is NULL and if it is (or might be), proceeding
> > with code that dereferences that same pointer is clearly a mistake.
> > This happens in sound/isa/sb/sb8_midi.c::snd_sb8dsp_midi_interrupt()
> > The patch below reworks the code so this unfortunate case doesn't happen.
>
> All callers of snd_sb8dsp_midi_interrupt() dereference "chip" right
> before calling.
So the "if (chip == NULL)" part should be removed to avoid confusion.
>
> > --- linux-2.6.17-rc4-git2-orig/sound/isa/sb/sb8_midi.c
> > +++ linux-2.6.17-rc4-git2/sound/isa/sb/sb8_midi.c
> > -irqreturn_t snd_sb8dsp_midi_interrupt(struct snd_sb * chip)
> > +irqreturn_t snd_sb8dsp_midi_interrupt(struct snd_sb *chip)
> > {
> > struct snd_rawmidi *rmidi;
> > int max = 64;
> > char byte;
> >
> > - if (chip == NULL || (rmidi = chip->rmidi) == NULL) {
> > + if (!chip)
> > + return IRQ_NONE;
> > +
> > + rmidi = chip->rmidi;
> > + if (!rmidi) {
> > inb(SBP(chip, DATA_AVAIL)); /* ack interrupt */
> > return IRQ_NONE;
> > }
Willy
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