On Fri, 09/07 18:15, Kevin Wolf wrote: > blk_unref() first decreases the refcount of the BlockBackend and calls > blk_delete() if the refcount reaches zero. Requests can still be in > flight at this point, they are only drained during blk_delete(): > > At this point, arbitrary callbacks can run. If any callback takes a > temporary BlockBackend reference, it will first increase the refcount to > 1 and then decrease it to 0 again, triggering another blk_delete(). This > will cause a use-after-free crash in the outer blk_delete(). > > Fix it by draining the BlockBackend before decreasing to refcount to 0. > Assert in blk_ref() that it never takes the first refcount (which would > mean that the BlockBackend is already being deleted). > > Signed-off-by: Kevin Wolf <kw...@redhat.com>
Good one! Reviewed-by: Fam Zheng <f...@redhat.com>
