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CVE-2022-49394 — blk-iolatency: Fix inflight count imbalances and IO hangs on offline

Affected: Linux

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

blk-iolatency: Fix inflight count imbalances and IO hangs on offline

iolatency needs to track the number of inflight IOs per cgroup. As this tracking can be expensive, it is disabled when no cgroup has iolatency configured for the device. To ensure that the inflight counters stay balanced, iolatency_set_limit() freezes the request_queue while manipulating the enabled counter, which ensures that no IO is in flight and thus all counters are zero.

Unfortunately, iolatency_set_limit() isn't the only place where the enabled counter is manipulated. iolatency_pd_offline() can also dec the counter and trigger disabling. As this disabling happens without freezing the q, this can easily happen while some IOs are in flight and thus leak the counts.

This can be easily demonstrated by turning on iolatency on an one empty cgroup while IOs are in flight in other cgroups and then removing the cgroup. Note that iolatency shouldn't have been enabled elsewhere in the system to ensure that removing the cgroup disables iolatency for the whole device.

The following keeps flipping on and off iolatency on sda:

echo +io > /sys/fs/cgroup/cgroup.subtree_control while true; do mkdir -p /sys/fs/cgroup/test echo '8:0 target=100000' > /sys/fs/cgroup/test/io.latency sleep 1 rmdir /sys/fs/cgroup/test sleep 1 done

and there's concurrent fio generating direct rand reads:

fio --name test --filename…

RHSA-2022:8267 — Red Hat Security Advisory: kernel security, bug fix, and enhancement update

kernel: off-path attacker may inject data or terminate victim's TCP session kernel: use-after-free vulnerability in function sco_sock_sendmsg() kernel: fix 'struct pid' leaks in 'dbgfs_target_ids_write()' kernel: mm/damon/dbgfs: protect targets destructions with kdamond_lock kernel: veth: ensure skb entering GRO are not cloned. kernel: inet: fully convert sk->sk_rx_dst to RCU rules kernel: irqchip/gic-v3-its: Fix potential VPE leak on error kernel: nvme-rdma: destroy cm id before destroy qp to avoid use after free kernel: ptp: Fix possible memory leak in ptp_clock_register() kernel: ethtool: do not perform operations on net devices being unregistered kernel: ethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce() kernel: net: nexthop: fix null pointer dereference when IPv6 is not enabled kernel: scsi: scsi_debug: Fix type in min_t to avoid stack OOB kernel: KVM: x86/mmu: Zap _all_ roots when unmapping gfn range in TDP MMU kernel: Revert "Revert "block, bfq: honor already-setup queue merges"" kernel: udmabuf: validate ubuf->pagecount kernel: drm/virtio: Ensure that objs is not NULL in virtio_gpu_array_put_free() kernel: smb2_ioctl_query_info NULL pointer dereference kernel: NULL pointer dereference in udf_expand_file_adinicbdue() during writeback kernel: swiotlb information leak with DMA_FROM_DEVICE kernel: uninitialized registers on stack in nft_do_chain can cause kernel pointer leakage to UM kernel: race condition in snd_pcm_hw_free leading to use-after-free kern…