On 5/21/20 2:46 PM, Marek Marczykowski-Górecki wrote: > On Thu, May 21, 2020 at 01:22:03PM -0400, Boris Ostrovsky wrote: >> On 3/19/20 3:14 AM, Juergen Gross wrote: >>> There have been reports of races in evtchn_from_irq() where the info >>> pointer has been NULL. >>> >>> Avoid that case by testing info before dereferencing it. >>> >>> In order to avoid accessing a just freed info structure do the kfree() >>> via kfree_rcu(). >> >> Looks like noone ever responded to this. >> >> >> This change looks fine but is there a background on the problem? I >> looked in the archives and didn't find the relevant discussion. > Here is the original bug report: > https://xen.markmail.org/thread/44apwkwzeme4uavo > Thanks. Do we know what the race is? Is it because an event is being delivered from a dying guest who is in the process of tearing down event channels? -boris
