s390/vfio-ap: Fix NULL deref in status_show() during queue probe

Summary

In the Linux kernel, the following vulnerability has been resolved: s390/vfio-ap: Fix NULL deref in status_show() during queue probe When vfio_ap_mdev_probe_queue() creates the sysfs attribute group, the queue's driver data has not yet been set. A concurrent read of the 'status' attribute can therefore call dev_get_drvdata() and get NULL, which is then passed directly to vfio_ap_mdev_for_queue() where q->apqn is unconditionally dereferenced, causing a NULL pointer dereference. Fix this by acquiring the update locks before calling sysfs_create_group(). The status_show() function acquires guests_lock before reading the driver data, so any concurrent read will block until after dev_set_drvdata() has been called and the update locks are released. As a bonus, the APQN no longer needs to be read from the queue struct after allocation — it can be read directly from apdev before allocation and stored in a local variable, which is then assigned to q->apqn once the allocation succeeds.

Timeline

1. Sep 16, 2026, 10:32 AM UTCCVE published
2. Oct 19, 2026, 8:55 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 260f3ea141382386e97611e7c2029bc013088ab1 · fixed in 31fa0a8a3c337ed2d200166d6926ab23c14f8b2e; From 260f3ea141382386e97611e7c2029bc013088ab1 · fixed in e102ce0f4af99dff769a4b1b4daa4cc6bd5ad2d9; From 260f3ea141382386e97611e7c2029bc013088ab1 · fixed in 69632952aca04caa71e49953b6949fc04e788e67; From 260f3ea141382386e97611e7c2029bc013088ab1 · fixed in 7db2511fc601ca3a6e3fb1bdce02261c3c3167c3; From 260f3ea141382386e97611e7c2029bc013088ab1 · fixed in dd6f4ef6f8a37412909ad787c837332fb070159c

• Linux Linux

  6.0

• KernelLinux

  From 6.0.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.51; From 6.19.0 · fixed in 7.2.5

References 5