CVE-2022-50552

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

blk-mq: use quiesced elevator switch when reinitializing queues

The hctx's run_work may be racing with the elevator switch when reinitializing hardware queues. The queue is merely frozen in this context, but that only prevents requests from allocating and doesn't stop the hctx work from running. The work may get an elevator pointer that's being torn down, and can result in use-after-free errors and kernel panics (example below). Use the quiesced elevator switch instead, and make the previous one static since it is now only used locally.

nvme nvme0: resetting controller nvme nvme0: 32/0/0 default/read/poll queues BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: errorcode(0x0000) - not-present page PGD 80000020c8861067 P4D 80000020c8861067 PUD 250f8c8067 PMD 0 Oops: 0000 [#1] SMP PTI Workqueue: kblockd blkmqrunworkfn RIP: 0010:kyberhas_work+0x29/0x70

...

Call Trace: __blkmqdodispatchsched+0x83/0x2b0 __blkmqscheddispatchrequests+0x12e/0x170 blkmqscheddispatchrequests+0x30/0x60 _blkmqrunhwqueue+0x2b/0x50 processonework+0x1ef/0x380 workerthread+0x2d/0x3e0