Messages in this thread | | | Date | Sun, 14 May 2006 18:24:09 +0400 | From | Alexey Dobriyan <> | Subject | Re: [PATCH] fix potential NULL pointer deref in snd_sb8dsp_midi_interrupt() |
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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.
> --- 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; > }
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