[ALSA] fix potential NULL pointer deref in snd_sb8dsp_midi_interrupt() (63eb1e4b) · Commits · 戴 / test

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. Also remove some blank comments. Found by the Coverity checker as bug #367 Patch is compile testted only due to lack of hardware. Signed-off-by:

Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by:

Takashi Iwai <tiwai@suse.de>

sound/isa/sb/sb8_midi.c

+7 −13

Original line number	Diff line number	Diff line
		@@ -32,9 +32,6 @@
		#include <sound/core.h>
		#include <sound/sb.h>

		/*

		*/

		irqreturn_t snd_sb8dsp_midi_interrupt(struct snd_sb *chip)
		{
		@@ -42,10 +39,15 @@ irqreturn_t snd_sb8dsp_midi_interrupt(struct snd_sb * chip)
		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;
		}

		spin_lock(&chip->midi_input_lock);
		while (max-- > 0) {
		if (inb(SBP(chip, DATA_AVAIL)) & 0x80) {
		@@ -59,10 +61,6 @@ irqreturn_t snd_sb8dsp_midi_interrupt(struct snd_sb * chip)
		return IRQ_HANDLED;
		}

		/*

		*/

		static int snd_sb8dsp_midi_input_open(struct snd_rawmidi_substream *substream)
		{
		unsigned long flags;
		@@ -252,10 +250,6 @@ static void snd_sb8dsp_midi_output_trigger(struct snd_rawmidi_substream *substre
		snd_sb8dsp_midi_output_write(substream);
		}

		/*

		*/

		static struct snd_rawmidi_ops snd_sb8dsp_midi_output =
		{
		.open = snd_sb8dsp_midi_output_open,

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