From: Sasha Levin Date: Fri, 2 Jan 2015 19:47:40 +0000 (-0500) Subject: virtio_pci: defer kfree until release callback X-Git-Tag: v3.2.67~70 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=119d5897cc5f9f73e352a1c647d21b9d506b8c0a;hp=ddabe0f7922dc94249030ce3f3f7cae9ef34dbe3;ds=sidebyside virtio_pci: defer kfree until release callback commit 63bd62a08ca45a0c804c3c89777edc7f76a2d6da upstream. A struct device which has just been unregistered can live on past the point at which a driver decides to drop it's initial reference to the kobject gained on allocation. This implies that when releasing a virtio device, we can't free a struct virtio_device until the underlying struct device has been released, which might not happen immediately on device_unregister(). Unfortunately, this is exactly what virtio pci does: it has an empty release callback, and frees memory immediately after unregistering the device. This causes an easy to reproduce crash if CONFIG_DEBUG_KOBJECT_RELEASE it enabled. To fix, free the memory only once we know the device is gone in the release callback. Signed-off-by: Sasha Levin Signed-off-by: Michael S. Tsirkin [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed