linux-kernel - [PATCH] ALSA: hda/hdmi - Fix duplicate unref of pci

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Message-Id: <77aa6c01aefe1ebc4004e87b0bc714f2759f15c4.1575985006.git.lukas@wunner.de>
Date:   Tue, 10 Dec 2019 14:39:50 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Jaroslav Kysela <perex@...ex.cz>,
        Alex Deucher <alexander.deucher@....com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: [PATCH] ALSA: hda/hdmi - Fix duplicate unref of pci_dev

Nicholas Johnson reports a null pointer deref as well as a refcount
underflow upon hot-removal of a Thunderbolt-attached AMD eGPU.
He's bisected the issue down to commit 586bc4aab878 ("ALSA: hda/hdmi -
fix vgaswitcheroo detection for AMD").

The commit iterates over PCI devices using pci_get_class() and
unreferences each device found, even though pci_get_class()
subsequently unreferences the device as well.  Fix it.

Fixes: 586bc4aab878 ("ALSA: hda/hdmi - fix vgaswitcheroo detection for AMD")
Link: https://lore.kernel.org/r/PSXP216MB0438BFEAA0617283A834E11580580@PSXP216MB0438.KORP216.PROD.OUTLOOK.COM/
Reported-and-tested-by: Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>
Signed-off-by: Lukas Wunner <lukas@...ner.de>
Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: Alexander Deucher <alexander.deucher@....com>
Cc: Bjorn Helgaas <helgaas@...nel.org>
---
 sound/pci/hda/hda_intel.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 35b4526f0d28..b856b89378ac 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1419,7 +1419,6 @@ static bool atpx_present(void)
 				return true;
 			}
 		}
-		pci_dev_put(pdev);
 	}
 	return false;
 }
-- 
2.24.0