Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

sound/virtio: Fix cancel_sync warnings on uninitialized work_structs

Betty reported hitting the following warning:

[ 8.709131][ T221] WARNING: CPU: 2 PID: 221 at kernel/workqueue.c:4182 ... [ 8.713282][ T221] Call trace: [ 8.713365][ T221] __flush_work+0x8d0/0x914 [ 8.713468][ T221] __cancel_work_sync+0xac/0xfc [ 8.713570][ T221] cancel_work_sync+0x24/0x34 [ 8.713667][ T221] virtsnd_remove+0xa8/0xf8 [virtio_snd ab15f34d0dd772f6d11327e08a81d46dc9c36276] [ 8.713868][ T221] virtsnd_probe+0x48c/0x664 [virtio_snd ab15f34d0dd772f6d11327e08a81d46dc9c36276] [ 8.714035][ T221] virtio_dev_probe+0x28c/0x390 [ 8.714139][ T221] really_probe+0x1bc/0x4c8 ...

It seems we're hitting the error path in virtsnd_probe(), which triggers a virtsnd_remove() which iterates over the substreams calling cancel_work_sync() on the elapsed_period work_struct.

Looking at the code, from earlier in: virtsnd_probe()->virtsnd_build_devs()->virtsnd_pcm_parse_cfg()

We set snd->nsubstreams, allocate the snd->substreams, and if we then hit an error on the info allocation or something in virtsnd_ctl_query_info() fails, we will exit without having initialized the elapsed_period work_struct.

When that error path unwinds we then call virtsnd_remove() which as long as the substreams array is allocated, will iterate through calling cancel_work_sync() on the uninitialized work struct hitting this warning.…