[alsa-devel] [PATCH 2/2] ALSA: hdspm: Fix zero-division

[Takashi Iwai]

HDSPM driver contains a code issuing zero-division potentially in
system sample rate ctl code.  This patch fixes it by not processing
a zero or invalid rate value as a divisor, as well as excluding the
invalid value to be passed via the given ctl element.

Cc: <stable at vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/pci/rme9652/hdspm.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/pci/rme9652/hdspm.c b/sound/pci/rme9652/hdspm.c
index b047b1ba48fd..a4a999a0317e 100644
--- a/sound/pci/rme9652/hdspm.c
+++ b/sound/pci/rme9652/hdspm.c
@@ -1601,6 +1601,9 @@ static void hdspm_set_dds_value(struct hdspm *hdspm, int rate)
 {
 	u64 n;
 
+	if (snd_BUG_ON(rate <= 0))
+		return;
+
 	if (rate >= 112000)
 		rate /= 4;
 	else if (rate >= 56000)
@@ -2215,6 +2218,8 @@ static int hdspm_get_system_sample_rate(struct hdspm *hdspm)
 		} else {
 			/* slave mode, return external sample rate */
 			rate = hdspm_external_sample_rate(hdspm);
+			if (!rate)
+				rate = hdspm->system_sample_rate;
 		}
 	}
 
@@ -2260,7 +2265,10 @@ static int snd_hdspm_put_system_sample_rate(struct snd_kcontrol *kcontrol,
 					    ucontrol)
 {
 	struct hdspm *hdspm = snd_kcontrol_chip(kcontrol);
+	int rate = ucontrol->value.integer.value[0];
 
+	if (rate < 27000 || rate > 207000)
+		return -EINVAL;
 	hdspm_set_dds_value(hdspm, ucontrol->value.integer.value[0]);
 	return 0;
 }
-- 
2.7.2