kernel/git/stable/linux.git/drivers/virtio/virtio.c, branch master

virtio: fix use-after-free in unregister_virtio_device()

2026-09-07T22:54:02+00:00

device_unregister() is device_del() plus put_device(). When the caller holds no extra reference, that drops the last one and runs the release callback, which for several transports frees the memory the embedded struct virtio_device sits in. unregister_virtio_device() then calls virtio_debug_device_exit(), which reads dev->debugfs_dir out of the freed object. Affected transports are the ones whose release callback frees and whose remove path takes no reference: virtio_mmio, virtio_vdpa, virtio_uml, mlxbf-tmfifo and virtio_ccw. virtio_pci is unaffected because virtio_pci_remove() brackets the call with get_device() and put_device(). Remove the debugfs entries before the device can go away. They are only accessed through the protected debugfs interface, so debugfs_remove_recursive() waits for in-progress file operations before returning. Tearing them down while the device is still alive is therefore safe. Reproduced on User-Mode Linux with CONFIG_KASAN and CONFIG_VIRTIO_DEBUG by unbinding a virtio-uml device: BUG: KASAN: slab-use-after-free in virtio_debug_device_exit+0x36/0x4d Read of size 8 at addr 00000000616e0b10 by task init/1 __asan_report_load8_noabort virtio_debug_device_exit+0x36/0x4d unregister_virtio_device+0x48/0x75 virtio_uml_remove platform_remove device_release_driver_internal unbind_store Freed by task 1: kfree virtio_uml_release_dev device_release kobject_put put_device device_unregister With this applied, the report is gone and unbind is clean. Fixes: 96a8326d69ff ("virtio: add debugfs infrastructure to allow to debug virtio features") Assisted-by: Claude:claude-opus-5 Signed-off-by: Karl Mehltretter Signed-off-by: Michael S. Tsirkin Message-ID: <20260821213953.76906-1-kmehltretter@gmail.com>

virtio: add virtio_device_shutdown() helper

2026-08-19T10:38:44+00:00

The generic virtio bus .shutdown handler, virtio_dev_shutdown(), breaks and resets a device once it has established that the driver has no .shutdown of its own. A driver that does implement .shutdown, to quiesce its own activity first, still needs the same break and reset afterwards and would otherwise have to open code it. Factor the break + synchronize_cbs + reset sequence out of virtio_dev_shutdown() into an exported virtio_device_shutdown() helper so such drivers can reuse it instead of duplicating the core logic. No functional change. Signed-off-by: Denis V. Lunev Reviewed-by: David Hildenbrand (Arm) Signed-off-by: Michael S. Tsirkin Message-ID: <20260624140846.2616797-2-den@openvz.org>

virtio: add num_vf callback to virtio_bus

2026-06-10T06:17:00+00:00

Recent QEMU versions added support for virtio SR-IOV emulation, allowing virtio devices to expose SR-IOV VFs to the guest. However, virtio_bus does not implement the num_vf callback of bus_type, causing dev_num_vf() to return 0 for virtio devices even when SR-IOV VFs are active. net/core/rtnetlink.c calls dev_num_vf(dev->dev.parent) to populate IFLA_NUM_VF in RTM_GETLINK responses. For a virtio-net device, dev.parent points to the virtio_device, whose busis virtio_bus. Without num_vf, SR-IOV VF information is silently omitted from tools that rely on rtnetlink, such as 'ip link show'. Add a num_vf callback that delegates to dev_num_vf(dev->parent), which in turn reaches the underlying transport (pci_bus_type for virtio-pci) where the actual VF count is tracked. Non-PCI transports are unaffected as dev_num_vf() returns 0 when no num_vf callback is present. Signed-off-by: Yui Washizu Signed-off-by: Michael S. Tsirkin Message-ID: <20260310061454.683894-1-yui.washidu@gmail.com>

virtio: clean up features qword/dword terms

2025-11-27T07:03:07+00:00

virtio pci uses word to mean "16 bits". mmio uses it to mean "32 bits". To avoid confusion, let's avoid the term in core virtio altogether. Just say U64 to mean "64 bit". Fixes: e7d4c1c5a546 ("virtio: introduce extended features") Cc: Paolo Abeni Acked-by: Jason Wang Message-ID: Signed-off-by: Michael S. Tsirkin

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

2025-08-01T21:17:48+00:00

Pull virtio updates from Michael Tsirkin: - vhost can now support legacy threading if enabled in Kconfig - vsock memory allocation strategies for large buffers have been improved, reducing pressure on kmalloc - vhost now supports the in-order feature. guest bits missed the merge window. - fixes, cleanups all over the place * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (30 commits) vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers vsock/virtio: Rename virtio_vsock_skb_rx_put() vhost/vsock: Allocate nonlinear SKBs for handling large receive buffers vsock/virtio: Move SKB allocation lower-bound check to callers vsock/virtio: Rename virtio_vsock_alloc_skb() vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put() vsock/virtio: Validate length in packet header before skb_put() vhost/vsock: Avoid allocating arbitrarily-sized SKBs vhost_net: basic in_order support vhost: basic in order support vhost: fail early when __vhost_add_used() fails vhost: Reintroduce kthread API and add mode selection vdpa: Fix IDR memory leak in VDUSE module exit vdpa/mlx5: Fix release of uninitialized resources on error path vhost-scsi: Fix check for inline_sg_cnt exceeding preallocated limit virtio: virtio_dma_buf: fix missing parameter documentation vhost: Fix typos vhost: vringh: Remove unused functions vhost: vringh: Remove unused iotlb functions ...

virtio: Fix typo in register_virtio_device() doc comment

2025-08-01T13:11:08+00:00

Corrected "suceess" to "success" in the function documentation for clarity. Signed-off-by: Alok Tiwari Acked-by: Jason Wang Message-Id: <20250529084350.3145699-1-alok.a.tiwari@oracle.com> Signed-off-by: Michael S. Tsirkin Reviewed-by: Xuan Zhuo

virtio: fix comments, readability

2025-08-01T13:11:07+00:00

Fix a couple of comments to match reality. Initialize config_driver_disabled to be consistent with other fields (note: the structure is already zero initialized, so this is not a bugfix as such). Signed-off-by: Michael S. Tsirkin Message-Id: <7b74a55a5f3dc066d954472f5b68c29022f11b43.1752094439.git.mst@redhat.com> Acked-by: Jason Wang

virtio: introduce extended features

2025-07-08T16:04:58+00:00

The virtio specifications allows for up to 128 bits for the device features. Soon we are going to use some of the 'extended' bits features (above 64) for the virtio_net driver. Introduce extended features as a fixed size array of u64. To minimize the diffstat allows legacy driver to access the low 64 bits via a transparent union. Introduce an extended get_extended_features configuration callback that devices supporting the extended features range must implement in place of the traditional one. Note that legacy and transport features don't need any change, as they are always in the low 64 bit range. Acked-by: Jason Wang Signed-off-by: Paolo Abeni

virtgpu: don't reset on shutdown

2025-04-18T14:05:49+00:00

It looks like GPUs are used after shutdown is invoked. Thus, breaking virtio gpu in the shutdown callback is not a good idea - guest hangs attempting to finish console drawing, with these warnings: [ 20.504464] WARNING: CPU: 0 PID: 568 at drivers/gpu/drm/virtio/virtgpu_vq.c:358 virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.505685] Modules linked in: nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 rfkill ip_set nf_tables nfnetlink vfat fat intel_rapl_msr intel_rapl_common intel_uncore_frequency_common nfit libnvdimm kvm_intel kvm rapl iTCO_wdt iTCO_vendor_support virtio_gpu virtio_dma_buf pcspkr drm_shmem_helper i2c_i801 drm_kms_helper lpc_ich i2c_smbus virtio_balloon joydev drm fuse xfs libcrc32c ahci libahci crct10dif_pclmul crc32_pclmul crc32c_intel libata virtio_net ghash_clmulni_intel net_failover virtio_blk failover serio_raw dm_mirror dm_region_hash dm_log dm_mod [ 20.511847] CPU: 0 PID: 568 Comm: kworker/0:3 Kdump: loaded Tainted: G W ------- --- 5.14.0-578.6675_1757216455.el9.x86_64 #1 [ 20.513157] Hardware name: Red Hat KVM/RHEL, BIOS edk2-20241117-3.el9 11/17/2024 [ 20.513918] Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] [ 20.514626] RIP: 0010:virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.515332] Code: 00 00 48 85 c0 74 0c 48 8b 78 08 48 89 ee e8 51 50 00 00 65 ff 0d 42 e3 74 3f 0f 85 69 ff ff ff 0f 1f 44 00 00 e9 5f ff ff ff <0f> 0b e9 3f ff ff ff 48 83 3c 24 00 74 0e 49 8b 7f 40 48 85 ff 74 [ 20.517272] RSP: 0018:ff34f0a8c0787ad8 EFLAGS: 00010282 [ 20.517820] RAX: 00000000fffffffb RBX: 0000000000000000 RCX: 0000000000000820 [ 20.518565] RDX: 0000000000000000 RSI: ff34f0a8c0787be0 RDI: ff218bef03a26300 [ 20.519308] RBP: ff218bef03a26300 R08: 0000000000000001 R09: ff218bef07224360 [ 20.520059] R10: 0000000000008dc0 R11: 0000000000000002 R12: ff218bef02630028 [ 20.520806] R13: ff218bef0263fb48 R14: ff218bef00cb8000 R15: ff218bef07224360 [ 20.521555] FS: 0000000000000000(0000) GS:ff218bef7ba00000(0000) knlGS:0000000000000000 [ 20.522397] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.522996] CR2: 000055ac4f7871c0 CR3: 000000010b9f2002 CR4: 0000000000771ef0 [ 20.523740] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 20.524477] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 [ 20.525223] PKRU: 55555554 [ 20.525515] Call Trace: [ 20.525777] [ 20.526003] ? show_trace_log_lvl+0x1c4/0x2df [ 20.526464] ? show_trace_log_lvl+0x1c4/0x2df [ 20.526925] ? virtio_gpu_queue_fenced_ctrl_buffer+0x82/0x2c0 [virtio_gpu] [ 20.527643] ? virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.528282] ? __warn+0x7e/0xd0 [ 20.528621] ? virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.529256] ? report_bug+0x100/0x140 [ 20.529643] ? handle_bug+0x3c/0x70 [ 20.530010] ? exc_invalid_op+0x14/0x70 [ 20.530421] ? asm_exc_invalid_op+0x16/0x20 [ 20.530862] ? virtio_gpu_queue_ctrl_sgs+0x236/0x290 [virtio_gpu] [ 20.531506] ? virtio_gpu_queue_ctrl_sgs+0x174/0x290 [virtio_gpu] [ 20.532148] virtio_gpu_queue_fenced_ctrl_buffer+0x82/0x2c0 [virtio_gpu] [ 20.532843] virtio_gpu_primary_plane_update+0x3e2/0x460 [virtio_gpu] [ 20.533520] drm_atomic_helper_commit_planes+0x108/0x320 [drm_kms_helper] [ 20.534233] drm_atomic_helper_commit_tail+0x45/0x80 [drm_kms_helper] [ 20.534914] commit_tail+0xd2/0x130 [drm_kms_helper] [ 20.535446] drm_atomic_helper_commit+0x11b/0x140 [drm_kms_helper] [ 20.536097] drm_atomic_commit+0xa4/0xe0 [drm] [ 20.536588] ? __pfx___drm_printfn_info+0x10/0x10 [drm] [ 20.537162] drm_atomic_helper_dirtyfb+0x192/0x270 [drm_kms_helper] [ 20.537823] drm_fbdev_shmem_helper_fb_dirty+0x43/0xa0 [drm_shmem_helper] [ 20.538536] drm_fb_helper_damage_work+0x87/0x160 [drm_kms_helper] [ 20.539188] process_one_work+0x194/0x380 [ 20.539612] worker_thread+0x2fe/0x410 [ 20.540007] ? __pfx_worker_thread+0x10/0x10 [ 20.540456] kthread+0xdd/0x100 [ 20.540791] ? __pfx_kthread+0x10/0x10 [ 20.541190] ret_from_fork+0x29/0x50 [ 20.541566] [ 20.541802] ---[ end trace 0000000000000000 ]--- It looks like the shutdown is called in the middle of console drawing, so we should either wait for it to finish, or let drm handle the shutdown. This patch implements this second option: Add an option for drivers to bypass the common break+reset handling. As DRM is careful to flush/synchronize outstanding buffers, it looks like GPU can just have a NOP there. Reviewed-by: Eric Auger Tested-by: Eric Auger Fixes: 8bd2fa086a04 ("virtio: break and reset virtio devices on device_shutdown()") Cc: Eric Auger Cc: Jocelyn Falempe Signed-off-by: Michael S. Tsirkin Message-Id: <8490dbeb6f79ed039e6c11d121002618972538a3.1744293540.git.mst@redhat.com>

virtio: break and reset virtio devices on device_shutdown()

2025-02-24T19:29:26+00:00

Hongyu reported a hang on kexec in a VM. QEMU reported invalid memory accesses during the hang. Invalid read at addr 0x102877002, size 2, region '(null)', reason: rejected Invalid write at addr 0x102877A44, size 2, region '(null)', reason: rejected ... It was traced down to virtio-console. Kexec works fine if virtio-console is not in use. The issue is that virtio-console continues to write to the MMIO even after underlying virtio-pci device is reset. Additionally, Eric noticed that IOMMUs are reset before devices, if devices are not reset on shutdown they continue to poke at guest memory and get errors from the IOMMU. Some devices get wedged then. The problem can be solved by breaking all virtio devices on virtio bus shutdown, then resetting them. Reported-by: Eric Auger Reported-by: Hongyu Ning Message-ID: Tested-by: Eric Auger Acked-by: Jason Wang Signed-off-by: Michael S. Tsirkin