FAILED: patch "[PATCH] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()" failed to apply to 4.9-stable tree

FAILED: patch "[PATCH] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()" failed to apply to 4.9-stable tree

[gregkh]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4df591b20b80cb77920953812d894db259d85bd7 Mon Sep 17 00:00:00 2001
From: Dexuan Cui <decui@microsoft.com>
Date: Fri, 21 Jun 2019 23:45:23 +0000
Subject: [PATCH] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()

Fix a use-after-free in hv_eject_device_work().

Fixes: 05f151a73ec2 ("PCI: hv: Fix a memory leak in hv_eject_device_work()")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 82acd6155adf..40b625458afa 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1875,6 +1875,7 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
 static void hv_eject_device_work(struct work_struct *work)
 {
 	struct pci_eject_response *ejct_pkt;
+	struct hv_pcibus_device *hbus;
 	struct hv_pci_dev *hpdev;
 	struct pci_dev *pdev;
 	unsigned long flags;
@@ -1885,6 +1886,7 @@ static void hv_eject_device_work(struct work_struct *work)
 	} ctxt;
 
 	hpdev = container_of(work, struct hv_pci_dev, wrk);
+	hbus = hpdev->hbus;
 
 	WARN_ON(hpdev->state != hv_pcichild_ejecting);
 
@@ -1895,8 +1897,7 @@ static void hv_eject_device_work(struct work_struct *work)
 	 * because hbus->pci_bus may not exist yet.
 	 */
 	wslot = wslot_to_devfn(hpdev->desc.win_slot.slot);
-	pdev = pci_get_domain_bus_and_slot(hpdev->hbus->sysdata.domain, 0,
-					   wslot);
+	pdev = pci_get_domain_bus_and_slot(hbus->sysdata.domain, 0, wslot);
 	if (pdev) {
 		pci_lock_rescan_remove();
 		pci_stop_and_remove_bus_device(pdev);
@@ -1904,9 +1905,9 @@ static void hv_eject_device_work(struct work_struct *work)
 		pci_unlock_rescan_remove();
 	}
 
-	spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
 	list_del(&hpdev->list_entry);
-	spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
 
 	if (hpdev->pci_slot)
 		pci_destroy_slot(hpdev->pci_slot);
@@ -1915,7 +1916,7 @@ static void hv_eject_device_work(struct work_struct *work)
 	ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
 	ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
 	ejct_pkt->wslot.slot = hpdev->desc.win_slot.slot;
-	vmbus_sendpacket(hpdev->hbus->hdev->channel, ejct_pkt,
+	vmbus_sendpacket(hbus->hdev->channel, ejct_pkt,
 			 sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,
 			 VM_PKT_DATA_INBAND, 0);
 
@@ -1924,7 +1925,9 @@ static void hv_eject_device_work(struct work_struct *work)
 	/* For the two refs got in new_pcichild_device() */
 	put_pcichild(hpdev);
 	put_pcichild(hpdev);
-	put_hvpcibus(hpdev->hbus);
+	/* hpdev has been freed. Do not use it any more. */
+
+	put_hvpcibus(hbus);
 }
 
 /**

RE: FAILED: patch "[PATCH] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()" failed to apply to 4.9-stable tree

[Dexuan Cui]

[-- Attachment #1: Type: text/plain, Size: 1318 bytes --]

> From: gregkh@linuxfoundation.org <gregkh@linuxfoundation.org>
> Sent: Tuesday, July 23, 2019 4:59 AM
> To: Dexuan Cui <decui@microsoft.com>; lorenzo.pieralisi@arm.com; Michael
> Kelley <mikelley@microsoft.com>
> Cc: stable@vger.kernel.org
> Subject: FAILED: patch "[PATCH] PCI: hv: Fix a use-after-free bug in
> hv_eject_device_work()" failed to apply to 4.9-stable tree
> 
> 
> The patch below does not apply to the 4.9-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> From 4df591b20b80cb77920953812d894db259d85bd7 Mon Sep 17 00:00:00
> 2001
> From: Dexuan Cui <decui@microsoft.com>
> Date: Fri, 21 Jun 2019 23:45:23 +0000
> Subject: [PATCH] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()

Hi,
To apply this patch to v4.9.186, we need to cherry-pick another patch first:
e74d2ebdda33 ("PCI: hv: Delete the device earlier from hbus->children for hot-remove")

Then I backported this commit (4df591b20)

Please see the two attachments for the two patches.
They can be cleanly applied to v4.9.186.

Thanks,
-- Dexuan

[-- Attachment #2: for-4.9.186-0001-PCI-hv-Delete-the-device-earlier-from-hbus-children-.patch --]
[-- Type: application/octet-stream, Size: 2416 bytes --]

From 70913034cdcf061020573d64d4890c3781c63b6b Mon Sep 17 00:00:00 2001
From: Dexuan Cui <decui@microsoft.com>
Date: Thu, 10 Nov 2016 07:19:52 +0000
Subject: [PATCH for-4.9.186 1/2] PCI: hv: Delete the device earlier from
 hbus->children for hot-remove
Reply-To: decui@microsoft.com

[ Upstream commit e74d2ebdda33b3bdd1826b5b92e9aa45bdf92bb3 ]

After we send a PCI_EJECTION_COMPLETE message to the host, the host will
immediately send us a PCI_BUS_RELATIONS message with
relations->device_count == 0, so pci_devices_present_work(), running on
another thread, can find the being-ejected device, mark the
hpdev->reported_missing to true, and run list_move_tail()/list_del() for
the device -- this races hv_eject_device_work() -> list_del().

Move the list_del() in hv_eject_device_work() to an earlier place, i.e.,
before we send PCI_EJECTION_COMPLETE, so later the
pci_devices_present_work() can't see the device.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jake Oshins <jakeo@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: Vitaly Kuznetsov <vkuznets@redhat.com>

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/pci/host/pci-hyperv.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 200b415..499461c 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1607,6 +1607,10 @@ static void hv_eject_device_work(struct work_struct *work)
 		pci_unlock_rescan_remove();
 	}
 
+	spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
+	list_del(&hpdev->list_entry);
+	spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
+
 	memset(&ctxt, 0, sizeof(ctxt));
 	ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
 	ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
@@ -1615,10 +1619,6 @@ static void hv_eject_device_work(struct work_struct *work)
 			 sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,
 			 VM_PKT_DATA_INBAND, 0);
 
-	spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
-	list_del(&hpdev->list_entry);
-	spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
-
 	put_pcichild(hpdev, hv_pcidev_ref_childlist);
 	put_pcichild(hpdev, hv_pcidev_ref_initial);
 	put_pcichild(hpdev, hv_pcidev_ref_pnp);
-- 
1.8.3.1


[-- Attachment #3: for-4.9.186-0002-PCI-hv-Fix-a-use-after-free-bug-in-hv_eject_device_w.patch --]
[-- Type: application/octet-stream, Size: 3012 bytes --]

From ec241858c53dd7fdc98a8f4ee4719bf64e0677f8 Mon Sep 17 00:00:00 2001
From: Dexuan Cui <decui@microsoft.com>
Date: Tue, 23 Jul 2019 17:30:41 -0700
Subject: [PATCH for-4.9.186 2/2] PCI: hv: Fix a use-after-free bug in
 hv_eject_device_work()
Reply-To: decui@microsoft.com

[ Upstream commit 4df591b20b80cb77920953812d894db259d85bd7 ]

Fix a use-after-free in hv_eject_device_work().

Fixes: 05f151a73ec2 ("PCI: hv: Fix a memory leak in hv_eject_device_work()")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: stable@vger.kernel.org

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/pci/host/pci-hyperv.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 499461c..a597619 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1575,6 +1575,7 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
 static void hv_eject_device_work(struct work_struct *work)
 {
 	struct pci_eject_response *ejct_pkt;
+	struct hv_pcibus_device *hbus;
 	struct hv_pci_dev *hpdev;
 	struct pci_dev *pdev;
 	unsigned long flags;
@@ -1585,6 +1586,7 @@ static void hv_eject_device_work(struct work_struct *work)
 	} ctxt;
 
 	hpdev = container_of(work, struct hv_pci_dev, wrk);
+	hbus = hpdev->hbus;
 
 	if (hpdev->state != hv_pcichild_ejecting) {
 		put_pcichild(hpdev, hv_pcidev_ref_pnp);
@@ -1598,8 +1600,7 @@ static void hv_eject_device_work(struct work_struct *work)
 	 * because hbus->pci_bus may not exist yet.
 	 */
 	wslot = wslot_to_devfn(hpdev->desc.win_slot.slot);
-	pdev = pci_get_domain_bus_and_slot(hpdev->hbus->sysdata.domain, 0,
-					   wslot);
+	pdev = pci_get_domain_bus_and_slot(hbus->sysdata.domain, 0, wslot);
 	if (pdev) {
 		pci_lock_rescan_remove();
 		pci_stop_and_remove_bus_device(pdev);
@@ -1607,22 +1608,24 @@ static void hv_eject_device_work(struct work_struct *work)
 		pci_unlock_rescan_remove();
 	}
 
-	spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
 	list_del(&hpdev->list_entry);
-	spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
 
 	memset(&ctxt, 0, sizeof(ctxt));
 	ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
 	ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
 	ejct_pkt->wslot.slot = hpdev->desc.win_slot.slot;
-	vmbus_sendpacket(hpdev->hbus->hdev->channel, ejct_pkt,
+	vmbus_sendpacket(hbus->hdev->channel, ejct_pkt,
 			 sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,
 			 VM_PKT_DATA_INBAND, 0);
 
 	put_pcichild(hpdev, hv_pcidev_ref_childlist);
 	put_pcichild(hpdev, hv_pcidev_ref_initial);
 	put_pcichild(hpdev, hv_pcidev_ref_pnp);
-	put_hvpcibus(hpdev->hbus);
+
+	/* hpdev has been freed. Do not use it any more. */
+	put_hvpcibus(hbus);
 }
 
 /**
-- 
1.8.3.1

Re: FAILED: patch "[PATCH] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()" failed to apply to 4.9-stable tree

[gregkh]

On Wed, Jul 24, 2019 at 12:59:01AM +0000, Dexuan Cui wrote:
> > From: gregkh@linuxfoundation.org <gregkh@linuxfoundation.org>
> > Sent: Tuesday, July 23, 2019 4:59 AM
> > To: Dexuan Cui <decui@microsoft.com>; lorenzo.pieralisi@arm.com; Michael
> > Kelley <mikelley@microsoft.com>
> > Cc: stable@vger.kernel.org
> > Subject: FAILED: patch "[PATCH] PCI: hv: Fix a use-after-free bug in
> > hv_eject_device_work()" failed to apply to 4.9-stable tree
> > 
> > 
> > The patch below does not apply to the 4.9-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > thanks,
> > 
> > greg k-h
> > 
> > ------------------ original commit in Linus's tree ------------------
> > 
> > From 4df591b20b80cb77920953812d894db259d85bd7 Mon Sep 17 00:00:00
> > 2001
> > From: Dexuan Cui <decui@microsoft.com>
> > Date: Fri, 21 Jun 2019 23:45:23 +0000
> > Subject: [PATCH] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()
> 
> Hi,
> To apply this patch to v4.9.186, we need to cherry-pick another patch first:
> e74d2ebdda33 ("PCI: hv: Delete the device earlier from hbus->children for hot-remove")
> 
> Then I backported this commit (4df591b20)
> 
> Please see the two attachments for the two patches.
> They can be cleanly applied to v4.9.186.

Now queued up, thanks.

greg k-h