CVE-2024-26698

In the Linux kernel, the following vulnerability has been resolved:
hv_netvsc: Fix race condition between netvsc_probe and netvsc_remove In
commit ac5047671758 (“hv_netvsc: Disable NAPI before closing the VMBus
channel”), napi_disable was getting called for all channels, including all
subchannels without confirming if they are enabled or not. This caused
hv_netvsc getting hung at napi_disable, when netvsc_probe() has finished
running but nvdev->subchan_work has not started yet. netvsc_subchan_work()
-> rndis_set_subchannel() has not created the sub-channels and because of
that netvsc_sc_open() is not running. netvsc_remove() calls
cancel_work_sync(&nvdev->subchan_work), for which netvsc_subchan_work did
not run. netif_napi_add() sets the bit NAPI_STATE_SCHED because it ensures
NAPI cannot be scheduled. Then netvsc_sc_open() -> napi_enable will clear
the NAPIF_STATE_SCHED bit, so it can be scheduled. napi_disable() does the
opposite. Now during netvsc_device_remove(), when napi_disable is called
for those subchannels, napi_disable gets stuck on infinite msleep. This fix
addresses this problem by ensuring that napi_disable() is not getting
called for non-enabled NAPI struct. But netif_napi_del() is still necessary
for these non-enabled NAPI struct for cleanup purpose. Call trace: [
654.559417] task:modprobe state:D stack: 0 pid: 2321 ppid: 1091
flags:0x00004002 [ 654.568030] Call Trace: [ 654.571221] <TASK> [
654.573790] __schedule+0x2d6/0x960 [ 654.577733] schedule+0x69/0xf0 [
654.581214] schedule_timeout+0x87/0x140 [ 654.585463] ?
__bpf_trace_tick_stop+0x20/0x20 [ 654.590291] msleep+0x2d/0x40 [
654.593625] napi_disable+0x2b/0x80 [ 654.597437]
netvsc_device_remove+0x8a/0x1f0 [hv_netvsc] [ 654.603935]
rndis_filter_device_remove+0x194/0x1c0 [hv_netvsc] [ 654.611101] ?
do_wait_intr+0xb0/0xb0 [ 654.615753] netvsc_remove+0x7c/0x120 [hv_netvsc] [
654.621675] vmbus_remove+0x27/0x40 [hv_vmbus]