[PATCH] mdev: fix daemon crash on reattach mdevs

[Erik Skultety]

On Tue, Jul 21, 2020 at 05:21:10PM +0800, Binfeng Wu wrote:
> Causing a crash when virMediatedDeviceListFindIndex because of
> some pointers in mgr->activeMediatedHostdevs become dangling 
> pointers if goto cleanup label in virMediatedDeviceListMarkDevices.
> 
> Reproduction scenario:
> 1. start vm1 with mdev1
> 2. start vm2 with mdev2, mdev1 (the order cannot be changed)
> 
> Backtrace:
> #0  0x0000ffffb8c36250 in strcmp
> #1  0x0000ffffb9b80754 in virMediatedDeviceListFindIndex
> #2  0x0000ffffb9b80870 in virMediatedDeviceListFind
> #3  0x0000ffffb9c9e168 in virHostdevReAttachMediatedDevices
> #4  0x0000ffff9949f724 in qemuHostdevReAttachMediatedDevices
> #5  0x0000ffff9949f7f8 in qemuHostdevReAttachDomainDevices
> #6  0x0000ffff994bcd70 in qemuProcessStop
> #7  0x0000ffff994bf4e0 in qemuProcessStart 

Sorry for the delay, I got my hands on a machine to investigate. Good
catch, it was a tricky one :).

I reworded the commit message a bit to provide more detailed info about
the bug and pushed.

Reviewed-by: Erik Skultety <eskultet at redhat.com>