AZL-66641

In the Linux kernel, the following vulnerability has been resolved:

PCI: pnv_php: Clean up allocated IRQs on unplug

When the root of a nested PCIe bridge configuration is unplugged, the pnv_php driver leaked the allocated IRQ resources for the child bridges' hotplug event notifications, resulting in a panic.

Fix this by walking all child buses and deallocating all its IRQ resources before calling pcihpremove_devices().

Also modify the lifetime of the workqueue at struct pnvphpslot::wq so that it is only destroyed in pnvphpfreeslot(), instead of pnvphpdisableirq(). This is required since pnvphpdisable_irq() will now be called by workers triggered by hot unplug interrupts, so the workqueue needs to stay allocated.

The abridged kernel panic that occurs without this patch is as follows:

WARNING: CPU: 0 PID: 687 at kernel/irq/msi.c:292 msidevicedatarelease+0x6c/0x9c CPU: 0 UID: 0 PID: 687 Comm: bash Not tainted 6.14.0-rc5+ #2 Call Trace: msidevicedatarelease+0x34/0x9c (unreliable) releasenodes+0x64/0x13c devresreleaseall+0xc0/0x140 devicedel+0x2d4/0x46c pcidestroydev+0x5c/0x194 pcihpremovedevices+0x90/0x128 pcihpremovedevices+0x44/0x128 pnvphpdisableslot+0x54/0xd4 powerwritefile+0xf8/0x18c pcislotattrstore+0x40/0x5c sysfskfwrite+0x64/0x78 kernfsfopwriteiter+0x1b0/0x290 vfswrite+0x3bc/0x50c ksyswrite+0x84/0x140 systemcallexception+0x124/0x230 systemcallvectoredcommon+0x15c/0x2ec

[bhelgaas: tidy comments]