From fed08d036f2aabd8d0c684439de37f8ebec2bbc2 Mon Sep 17 00:00:00 2001
From: Jody Bruchon <jody@nctritech.com>
Date: Sat, 6 Feb 2010 10:46:26 -0500
Subject: [PATCH] ALSA: hda-intel: Avoid divide by zero crash
On my AMD780V chipset, hda_intel.c can crash the kernel with a divide by
zero
for as-yet unknown reasons. A simple check for zero prevents it, though
the problem that causes it remains. Since the workaround is harmless and
won't affect anyone except victims of this bug, it should be safe;
moreover,
because this crash can be triggered by a user-mode application, there are
denial of service implications on the systems affected by the bug without
the patch.
Signed-off-by: Jody Bruchon <jody@nctritech.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/pci/hda/hda_intel.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index b8faa6dc5abe..e767c3f395ab 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1893,6 +1893,12 @@ static int azx_position_ok(struct azx *chip, struct azx_dev *azx_dev)
if (!bdl_pos_adj[chip->dev_index])
return 1; /* no delayed ack */
+ if (azx_dev->period_bytes == 0) {
+ printk(KERN_WARNING
+ "hda-intel: Divide by zero was avoided "
+ "in azx_dev->period_bytes.\n");
+ return 0;
+ }
if (pos % azx_dev->period_bytes > azx_dev->period_bytes / 2)
return 0; /* NG - it's below the period boundary */
return 1; /* OK, it's fine */
--
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