linux-stable.git/drivers/uio, branch linux-5.10.y Linux kernel stable tree uio_hv_generic: Set event for all channels on the device 2025-12-06T21:08:21+00:00 Long Li longli@microsoft.com 2025-03-10T22:12:01+00:00 d01fb18bdfa39c1293fe687aa33ae9e37bd03d74 commit d062463edf1770427dc2d637df4088df4835aa47 upstream. Hyper-V may offer a non latency sensitive device with subchannels without monitor bit enabled. The decision is entirely on the Hyper-V host not configurable within guest. When a device has subchannels, also signal events for the subchannel if its monitor bit is disabled. This patch also removes the memory barrier when monitor bit is enabled as it is not necessary. The memory barrier is only needed between setting up interrupt mask and calling vmbus_set_event() when monitor bit is disabled. Signed-off-by: Long Li <longli@microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com> Link: https://lore.kernel.org/r/1741644721-20389-1-git-send-email-longli@linuxonhyperv.com Fixes: b15b7d2a1b09 ("uio_hv_generic: Let userspace take care of interrupt mask") Closes: https://bugs.debian.org/1120602 Signed-off-by: Naman Jain <namjain@linux.microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d062463edf1770427dc2d637df4088df4835aa47 upstream.

Hyper-V may offer a non latency sensitive device with subchannels without
monitor bit enabled. The decision is entirely on the Hyper-V host not
configurable within guest.

When a device has subchannels, also signal events for the subchannel
if its monitor bit is disabled.

This patch also removes the memory barrier when monitor bit is enabled
as it is not necessary. The memory barrier is only needed between
setting up interrupt mask and calling vmbus_set_event() when monitor
bit is disabled.

Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Link: https://lore.kernel.org/r/1741644721-20389-1-git-send-email-longli@linuxonhyperv.com
Fixes: b15b7d2a1b09 ("uio_hv_generic: Let userspace take care of interrupt mask")
Closes: https://bugs.debian.org/1120602
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uio_hv_generic: Let userspace take care of interrupt mask 2025-10-29T13:01:08+00:00 Naman Jain namjain@linux.microsoft.com 2025-08-28T04:42:00+00:00 65d40acd911c7011745cbbd2aaac34eb5266d11e commit b15b7d2a1b09ef5428a8db260251897405a19496 upstream. Remove the logic to set interrupt mask by default in uio_hv_generic driver as the interrupt mask value is supposed to be controlled completely by the user space. If the mask bit gets changed by the driver, concurrently with user mode operating on the ring, the mask bit may be set when it is supposed to be clear, and the user-mode driver will miss an interrupt which will cause a hang. For eg- when the driver sets inbound ring buffer interrupt mask to 1, the host does not interrupt the guest on the UIO VMBus channel. However, setting the mask does not prevent the host from putting a message in the inbound ring buffer. So let’s assume that happens, the host puts a message into the ring buffer but does not interrupt. Subsequently, the user space code in the guest sets the inbound ring buffer interrupt mask to 0, saying “Hey, I’m ready for interrupts”. User space code then calls pread() to wait for an interrupt. Then one of two things happens: * The host never sends another message. So the pread() waits forever. * The host does send another message. But because there’s already a message in the ring buffer, it doesn’t generate an interrupt. This is the correct behavior, because the host should only send an interrupt when the inbound ring buffer transitions from empty to not-empty. Adding an additional message to a ring buffer that is not empty is not supposed to generate an interrupt on the guest. Since the guest is waiting in pread() and not removing messages from the ring buffer, the pread() waits forever. This could be easily reproduced in hv_fcopy_uio_daemon if we delay setting interrupt mask to 0. Similarly if hv_uio_channel_cb() sets the interrupt_mask to 1, there’s a race condition. Once user space empties the inbound ring buffer, but before user space sets interrupt_mask to 0, the host could put another message in the ring buffer but it wouldn’t interrupt. Then the next pread() would hang. Fix these by removing all instances where interrupt_mask is changed, while keeping the one in set_event() unchanged to enable userspace control the interrupt mask by writing 0/1 to /dev/uioX. Fixes: 95096f2fbd10 ("uio-hv-generic: new userspace i/o driver for VMBus") Suggested-by: John Starks <jostarks@microsoft.com> Signed-off-by: Naman Jain <namjain@linux.microsoft.com> Cc: stable@vger.kernel.org Reviewed-by: Michael Kelley <mhklinux@outlook.com> Reviewed-by: Long Li <longli@microsoft.com> Reviewed-by: Tianyu Lan <tiala@microsoft.com> Tested-by: Tianyu Lan <tiala@microsoft.com> Link: https://lore.kernel.org/r/20250828044200.492030-1-namjain@linux.microsoft.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b15b7d2a1b09ef5428a8db260251897405a19496 upstream.

Remove the logic to set interrupt mask by default in uio_hv_generic
driver as the interrupt mask value is supposed to be controlled
completely by the user space. If the mask bit gets changed
by the driver, concurrently with user mode operating on the ring,
the mask bit may be set when it is supposed to be clear, and the
user-mode driver will miss an interrupt which will cause a hang.

For eg- when the driver sets inbound ring buffer interrupt mask to 1,
the host does not interrupt the guest on the UIO VMBus channel.
However, setting the mask does not prevent the host from putting a
message in the inbound ring buffer. So let’s assume that happens,
the host puts a message into the ring buffer but does not interrupt.

Subsequently, the user space code in the guest sets the inbound ring
buffer interrupt mask to 0, saying “Hey, I’m ready for interrupts”.
User space code then calls pread() to wait for an interrupt.
Then one of two things happens:

* The host never sends another message. So the pread() waits forever.
* The host does send another message. But because there’s already a
  message in the ring buffer, it doesn’t generate an interrupt.
  This is the correct behavior, because the host should only send an
  interrupt when the inbound ring buffer transitions from empty to
  not-empty. Adding an additional message to a ring buffer that is not
  empty is not supposed to generate an interrupt on the guest.
  Since the guest is waiting in pread() and not removing messages from
  the ring buffer, the pread() waits forever.

This could be easily reproduced in hv_fcopy_uio_daemon if we delay
setting interrupt mask to 0.

Similarly if hv_uio_channel_cb() sets the interrupt_mask to 1,
there’s a race condition. Once user space empties the inbound ring
buffer, but before user space sets interrupt_mask to 0, the host could
put another message in the ring buffer but it wouldn’t interrupt.
Then the next pread() would hang.

Fix these by removing all instances where interrupt_mask is changed,
while keeping the one in set_event() unchanged to enable userspace
control the interrupt mask by writing 0/1 to /dev/uioX.

Fixes: 95096f2fbd10 ("uio-hv-generic: new userspace i/o driver for VMBus")
Suggested-by: John Starks <jostarks@microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Cc: stable@vger.kernel.org
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Long Li <longli@microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Tested-by: Tianyu Lan <tiala@microsoft.com>
Link: https://lore.kernel.org/r/20250828044200.492030-1-namjain@linux.microsoft.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uio_hv_generic: Fix another memory leak in error handling paths 2025-08-28T14:22:57+00:00 Christophe JAILLET christophe.jaillet@wanadoo.fr 2021-05-09T07:13:12+00:00 261bbd90cc53d2835343f056770156cf1e82cf03 commit 0b0226be3a52dadd965644bc52a807961c2c26df upstream. Memory allocated by 'vmbus_alloc_ring()' at the beginning of the probe function is never freed in the error handling path. Add the missing 'vmbus_free_ring()' call. Note that it is already freed in the .remove function. Fixes: cdfa835c6e5e ("uio_hv_generic: defer opening vmbus until first use") Cc: stable <stable@vger.kernel.org> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Link: https://lore.kernel.org/r/0d86027b8eeed8e6360bc3d52bcdb328ff9bdca1.1620544055.git.christophe.jaillet@wanadoo.fr [Shivani: Modified to apply on 5.10.y] Signed-off-by: Shivani Agarwal <shivani.agarwal@broadcom.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0b0226be3a52dadd965644bc52a807961c2c26df upstream.

Memory allocated by 'vmbus_alloc_ring()' at the beginning of the probe
function is never freed in the error handling path.

Add the missing 'vmbus_free_ring()' call.

Note that it is already freed in the .remove function.

Fixes: cdfa835c6e5e ("uio_hv_generic: defer opening vmbus until first use")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/0d86027b8eeed8e6360bc3d52bcdb328ff9bdca1.1620544055.git.christophe.jaillet@wanadoo.fr
[Shivani: Modified to apply on 5.10.y]
Signed-off-by: Shivani Agarwal <shivani.agarwal@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uio_hv_generic: Align ring size to system page 2025-07-17T16:27:40+00:00 Long Li longli@microsoft.com 2025-05-06T00:56:35+00:00 3d19fa73b1302e156a9542bd9f983a2cd83ded91 [ Upstream commit 0315fef2aff9f251ddef8a4b53db9187429c3553 ] Following the ring header, the ring data should align to system page boundary. Adjust the size if necessary. Cc: stable@vger.kernel.org Fixes: 95096f2fbd10 ("uio-hv-generic: new userspace i/o driver for VMBus") Signed-off-by: Long Li <longli@microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/1746492997-4599-4-git-send-email-longli@linuxonhyperv.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1746492997-4599-4-git-send-email-longli@linuxonhyperv.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 0315fef2aff9f251ddef8a4b53db9187429c3553 ]

Following the ring header, the ring data should align to system page
boundary. Adjust the size if necessary.

Cc: stable@vger.kernel.org
Fixes: 95096f2fbd10 ("uio-hv-generic: new userspace i/o driver for VMBus")
Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1746492997-4599-4-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1746492997-4599-4-git-send-email-longli@linuxonhyperv.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
uio_hv_generic: Query the ringbuffer size for device 2025-07-17T16:27:40+00:00 Saurabh Sengar ssengar@linux.microsoft.com 2024-03-30T08:51:58+00:00 6d748a084cdfd9217be6e166be994eb7d55bbdf7 [ Upstream commit e566ed5b64177a0c07b677568f623ed31d23406d ] Query the ring buffer size from pre defined table per device and use that value for allocating the ring buffer for that device. Keep the size as current default which is 2 MB if the device doesn't have any preferred ring size. Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com> Reviewed-by: Long Li <longli@microsoft.com> Link: https://lore.kernel.org/r/1711788723-8593-3-git-send-email-ssengar@linux.microsoft.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Stable-dep-of: 0315fef2aff9 ("uio_hv_generic: Align ring size to system page") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e566ed5b64177a0c07b677568f623ed31d23406d ]

Query the ring buffer size from pre defined table per device
and use that value for allocating the ring buffer for that
device. Keep the size as current default which is 2 MB if
the device doesn't have any preferred ring size.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Link: https://lore.kernel.org/r/1711788723-8593-3-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 0315fef2aff9 ("uio_hv_generic: Align ring size to system page")
Signed-off-by: Sasha Levin <sashal@kernel.org>
uio: uio_hv_generic: use devm_kzalloc() for private data alloc 2025-07-17T16:27:40+00:00 Alexandru Ardelean alexandru.ardelean@analog.com 2020-11-19T15:49:03+00:00 4564cc9afe7df34e1706647ba43271beb1342cae [ Upstream commit 74e71964b1a9ffd34fa4b6ec8f2fa13e7cf0ac7a ] This is a minor cleanup for the management of the private object of this driver. The allocation can be tied to the life-time of the hv_device object. This cleans up a bit the exit & error paths, since the object doesn't need to be explicitly free'd anymore. Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com> Link: https://lore.kernel.org/r/20201119154903.82099-4-alexandru.ardelean@analog.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Stable-dep-of: 0315fef2aff9 ("uio_hv_generic: Align ring size to system page") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 74e71964b1a9ffd34fa4b6ec8f2fa13e7cf0ac7a ]

This is a minor cleanup for the management of the private object of this
driver. The allocation can be tied to the life-time of the hv_device
object.
This cleans up a bit the exit & error paths, since the object doesn't need
to be explicitly free'd anymore.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20201119154903.82099-4-alexandru.ardelean@analog.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 0315fef2aff9 ("uio_hv_generic: Align ring size to system page")
Signed-off-by: Sasha Levin <sashal@kernel.org>
uio_hv_generic: Use correct size for interrupt and monitor pages 2025-06-27T10:04:14+00:00 Long Li longli@microsoft.com 2025-05-06T00:56:34+00:00 6180c8f19164a103c59184993b581858bc132df6 commit c951ab8fd3589cf6991ed4111d2130816f2e3ac2 upstream. Interrupt and monitor pages should be in Hyper-V page size (4k bytes). This can be different from the system page size. This size is read and used by the user-mode program to determine the mapped data region. An example of such user-mode program is the VMBus driver in DPDK. Cc: stable@vger.kernel.org Fixes: 95096f2fbd10 ("uio-hv-generic: new userspace i/o driver for VMBus") Signed-off-by: Long Li <longli@microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/1746492997-4599-3-git-send-email-longli@linuxonhyperv.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1746492997-4599-3-git-send-email-longli@linuxonhyperv.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c951ab8fd3589cf6991ed4111d2130816f2e3ac2 upstream.

Interrupt and monitor pages should be in Hyper-V page size (4k bytes).
This can be different from the system page size.

This size is read and used by the user-mode program to determine the
mapped data region. An example of such user-mode program is the VMBus
driver in DPDK.

Cc: stable@vger.kernel.org
Fixes: 95096f2fbd10 ("uio-hv-generic: new userspace i/o driver for VMBus")
Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1746492997-4599-3-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1746492997-4599-3-git-send-email-longli@linuxonhyperv.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Drivers: hv: vmbus: Fix rescind handling in uio_hv_generic 2024-09-12T09:06:50+00:00 Naman Jain namjain@linux.microsoft.com 2024-08-29T07:13:12+00:00 359ea5edc9198a50b3be99d77a380deca19e579a commit 6fd28941447bf2c8ca0f26fda612a1cabc41663f upstream. Rescind offer handling relies on rescind callbacks for some of the resources cleanup, if they are registered. It does not unregister vmbus device for the primary channel closure, when callback is registered. Without it, next onoffer does not come, rescind flag remains set and device goes to unusable state. Add logic to unregister vmbus for the primary channel in rescind callback to ensure channel removal and relid release, and to ensure that next onoffer can be received and handled properly. Cc: stable@vger.kernel.org Fixes: ca3cda6fcf1e ("uio_hv_generic: add rescind support") Signed-off-by: Naman Jain <namjain@linux.microsoft.com> Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com> Link: https://lore.kernel.org/r/20240829071312.1595-3-namjain@linux.microsoft.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6fd28941447bf2c8ca0f26fda612a1cabc41663f upstream.

Rescind offer handling relies on rescind callbacks for some of the
resources cleanup, if they are registered. It does not unregister
vmbus device for the primary channel closure, when callback is
registered. Without it, next onoffer does not come, rescind flag
remains set and device goes to unusable state.

Add logic to unregister vmbus for the primary channel in rescind callback
to ensure channel removal and relid release, and to ensure that next
onoffer can be received and handled properly.

Cc: stable@vger.kernel.org
Fixes: ca3cda6fcf1e ("uio_hv_generic: add rescind support")
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Link: https://lore.kernel.org/r/20240829071312.1595-3-namjain@linux.microsoft.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uio_hv_generic: Fix kernel NULL pointer dereference in hv_uio_rescind 2024-09-12T09:06:50+00:00 Saurabh Sengar ssengar@linux.microsoft.com 2024-08-29T07:13:11+00:00 1d8e020e51ab07e40f9dd00b52f1da7d96fec04c commit fb1adbd7e50f3d2de56d0a2bb0700e2e819a329e upstream. For primary VM Bus channels, primary_channel pointer is always NULL. This pointer is valid only for the secondary channels. Also, rescind callback is meant for primary channels only. Fix NULL pointer dereference by retrieving the device_obj from the parent for the primary channel. Cc: stable@vger.kernel.org Fixes: ca3cda6fcf1e ("uio_hv_generic: add rescind support") Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com> Signed-off-by: Naman Jain <namjain@linux.microsoft.com> Link: https://lore.kernel.org/r/20240829071312.1595-2-namjain@linux.microsoft.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit fb1adbd7e50f3d2de56d0a2bb0700e2e819a329e upstream.

For primary VM Bus channels, primary_channel pointer is always NULL. This
pointer is valid only for the secondary channels. Also, rescind callback
is meant for primary channels only.

Fix NULL pointer dereference by retrieving the device_obj from the parent
for the primary channel.

Cc: stable@vger.kernel.org
Fixes: ca3cda6fcf1e ("uio_hv_generic: add rescind support")
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Link: https://lore.kernel.org/r/20240829071312.1595-2-namjain@linux.microsoft.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uio: Fix use-after-free in uio_open 2024-01-25T22:37:38+00:00 Guanghui Feng guanghuifeng@linux.alibaba.com 2023-12-21T09:57:43+00:00 5e0be1229ae199ebb90b33102f74a0f22d152570 commit 0c9ae0b8605078eafc3bea053cc78791e97ba2e2 upstream. core-1 core-2 ------------------------------------------------------- uio_unregister_device uio_open idev = idr_find() device_unregister(&idev->dev) put_device(&idev->dev) uio_device_release get_device(&idev->dev) kfree(idev) uio_free_minor(minor) uio_release put_device(&idev->dev) kfree(idev) ------------------------------------------------------- In the core-1 uio_unregister_device(), the device_unregister will kfree idev when the idev->dev kobject ref is 1. But after core-1 device_unregister, put_device and before doing kfree, the core-2 may get_device. Then: 1. After core-1 kfree idev, the core-2 will do use-after-free for idev. 2. When core-2 do uio_release and put_device, the idev will be double freed. To address this issue, we can get idev atomic & inc idev reference with minor_lock. Fixes: 57c5f4df0a5a ("uio: fix crash after the device is unregistered") Cc: stable <stable@kernel.org> Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Link: https://lore.kernel.org/r/1703152663-59949-1-git-send-email-guanghuifeng@linux.alibaba.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0c9ae0b8605078eafc3bea053cc78791e97ba2e2 upstream.

core-1				core-2
-------------------------------------------------------
uio_unregister_device		uio_open
				idev = idr_find()
device_unregister(&idev->dev)
put_device(&idev->dev)
uio_device_release
				get_device(&idev->dev)
kfree(idev)
uio_free_minor(minor)
				uio_release
				put_device(&idev->dev)
				kfree(idev)
-------------------------------------------------------

In the core-1 uio_unregister_device(), the device_unregister will kfree
idev when the idev->dev kobject ref is 1. But after core-1
device_unregister, put_device and before doing kfree, the core-2 may
get_device. Then:
1. After core-1 kfree idev, the core-2 will do use-after-free for idev.
2. When core-2 do uio_release and put_device, the idev will be double
   freed.

To address this issue, we can get idev atomic & inc idev reference with
minor_lock.

Fixes: 57c5f4df0a5a ("uio: fix crash after the device is unregistered")
Cc: stable <stable@kernel.org>
Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/1703152663-59949-1-git-send-email-guanghuifeng@linux.alibaba.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>