From: Lukas Wunner <lukas@wunner.de> To: "Deucher, Alexander" <Alexander.Deucher@amd.com> Cc: Takashi Iwai <tiwai@suse.de>, Jaroslav Kysela <perex@perex.cz>, Mika Westerberg <mika.westerberg@linux.intel.com>, Bjorn Helgaas <helgaas@kernel.org>, Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>, "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org> Subject: Re: [PATCH] ALSA: hda/hdmi - Fix duplicate unref of pci_dev Date: Tue, 10 Dec 2019 16:46:49 +0100 [thread overview] Message-ID: <20191210154649.o3vsqzrtofhvcjrl@wunner.de> (raw) In-Reply-To: <MWHPR12MB1358AEEBD730A4EDA78894E6F75B0@MWHPR12MB1358.namprd12.prod.outlook.com> On Tue, Dec 10, 2019 at 03:34:27PM +0000, Deucher, Alexander wrote: > > 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. > > The pci_dev_put() a few lines above should probably be dropped as well. That one looks fine to me. The refcount is already increased in the caller get_bound_vga() via pci_get_domain_bus_and_slot() and it's increased again in atpx_present() via pci_get_class(). It needs to be decremented in atpx_present() to avoid leaking a ref. Thanks, Lukas > > 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
WARNING: multiple messages have this Message-ID (diff)
From: Lukas Wunner <lukas@wunner.de> To: "Deucher, Alexander" <Alexander.Deucher@amd.com> Cc: "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>, Takashi Iwai <tiwai@suse.de>, "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>, Bjorn Helgaas <helgaas@kernel.org>, Mika Westerberg <mika.westerberg@linux.intel.com> Subject: Re: [alsa-devel] [PATCH] ALSA: hda/hdmi - Fix duplicate unref of pci_dev Date: Tue, 10 Dec 2019 16:46:49 +0100 [thread overview] Message-ID: <20191210154649.o3vsqzrtofhvcjrl@wunner.de> (raw) In-Reply-To: <MWHPR12MB1358AEEBD730A4EDA78894E6F75B0@MWHPR12MB1358.namprd12.prod.outlook.com> On Tue, Dec 10, 2019 at 03:34:27PM +0000, Deucher, Alexander wrote: > > 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. > > The pci_dev_put() a few lines above should probably be dropped as well. That one looks fine to me. The refcount is already increased in the caller get_bound_vga() via pci_get_domain_bus_and_slot() and it's increased again in atpx_present() via pci_get_class(). It needs to be decremented in atpx_present() to avoid leaking a ref. Thanks, Lukas > > 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 _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
next prev parent reply other threads:[~2019-12-10 15:46 UTC|newest] Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-09 12:34 Linux v5.5 serious PCI bug Nicholas Johnson 2019-12-09 12:37 ` Pavel Machek 2019-12-09 13:07 ` Nicholas Johnson 2019-12-09 13:12 ` mika.westerberg 2019-12-09 13:29 ` Nicholas Johnson 2019-12-09 13:33 ` Nicholas Johnson 2019-12-10 7:28 ` mika.westerberg 2019-12-10 12:00 ` Nicholas Johnson 2019-12-10 12:29 ` Lukas Wunner 2019-12-10 12:46 ` Takashi Iwai 2019-12-11 7:33 ` Jiasen Lin 2019-12-10 12:52 ` Nicholas Johnson 2019-12-10 12:34 ` mika.westerberg 2019-12-10 13:39 ` [PATCH] ALSA: hda/hdmi - Fix duplicate unref of pci_dev Lukas Wunner 2019-12-10 13:39 ` [alsa-devel] " Lukas Wunner 2019-12-10 13:41 ` Takashi Iwai 2019-12-10 13:41 ` [alsa-devel] " Takashi Iwai 2019-12-10 13:47 ` Nicholas Johnson 2019-12-10 13:47 ` [alsa-devel] " Nicholas Johnson 2019-12-10 13:50 ` Takashi Iwai 2019-12-10 13:50 ` [alsa-devel] " Takashi Iwai 2019-12-10 15:34 ` Deucher, Alexander 2019-12-10 15:34 ` [alsa-devel] " Deucher, Alexander 2019-12-10 15:46 ` Lukas Wunner [this message] 2019-12-10 15:46 ` Lukas Wunner 2019-12-10 15:53 ` Deucher, Alexander 2019-12-10 15:53 ` [alsa-devel] " Deucher, Alexander 2019-12-10 16:10 ` Takashi Iwai 2019-12-10 16:10 ` [alsa-devel] " Takashi Iwai 2019-12-10 16:51 ` Deucher, Alexander 2019-12-10 16:51 ` [alsa-devel] " Deucher, Alexander 2019-12-10 16:13 ` Lukas Wunner 2019-12-10 16:13 ` [alsa-devel] " Lukas Wunner
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