On Tue, Nov 23, 2021 at 11:12 AM Parav Pandit [off-list ref] wrote:

quoted

From: Longpeng(Mike) <redacted>
Sent: Monday, November 22, 2021 5:52 PM

From: Longpeng <redacted>

The system will crash if we put an uninitialized iova_domain, this could
happen when an error occurs before initializing the iova_domain in
vdpasim_create().

BUG: kernel NULL pointer dereference, address: 0000000000000000 ...
RIP: 0010:__cpuhp_state_remove_instance+0x96/0x1c0
...
Call Trace:
 <TASK>
 put_iova_domain+0x29/0x220
 vdpasim_free+0xd1/0x120 [vdpa_sim]
 vdpa_release_dev+0x21/0x40 [vdpa]
 device_release+0x33/0x90
 kobject_release+0x63/0x160
 vdpasim_create+0x127/0x2a0 [vdpa_sim]
 vdpasim_net_dev_add+0x7d/0xfe [vdpa_sim_net]
 vdpa_nl_cmd_dev_add_set_doit+0xe1/0x1a0 [vdpa]
 genl_family_rcv_msg_doit+0x112/0x140
 genl_rcv_msg+0xdf/0x1d0
 ...

So we must make sure the iova_domain is already initialized before put it.

In addition, we may get the following warning in this case:
WARNING: ... drivers/iommu/iova.c:344 iova_cache_put+0x58/0x70

So we must make sure the iova_cache_put() is invoked only if the
iova_cache_get() is already invoked. Let's fix it together.

Signed-off-by: Longpeng <redacted>

Can you please add the fixes tag here so that older kernels can take this fix?

I guess it's 4080fc106750 ("vdpa_sim: use iova module to allocate IOVA
addresses")

Thanks

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