CVE-2022-48895

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

iommu/arm-smmu: Dont unregister on shutdown

Michael Walle says he noticed the following stack trace while performing a shutdown with reboot -f. He suggests he got lucky and just hit the correct spot for the reboot while there was a packet transmission in flight.

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000098 CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 6.1.0-rc5-00088-gf3600ff8e322 #1930 Hardware name: Kontron KBox A-230-LS (DT) pc : iommu_get_dma_domain+0x14/0x20 lr : iommu_dma_map_page+0x9c/0x254 Call trace: iommu_get_dma_domain+0x14/0x20 dma_map_page_attrs+0x1ec/0x250 enetc_start_xmit+0x14c/0x10b0 enetc_xmit+0x60/0xdc dev_hard_start_xmit+0xb8/0x210 sch_direct_xmit+0x11c/0x420 __dev_queue_xmit+0x354/0xb20 ip6_finish_output2+0x280/0x5b0 __ip6_finish_output+0x15c/0x270 ip6_output+0x78/0x15c NF_HOOK.constprop.0+0x50/0xd0 mld_sendpack+0x1bc/0x320 mld_ifc_work+0x1d8/0x4dc process_one_work+0x1e8/0x460 worker_thread+0x178/0x534 kthread+0xe0/0xe4 ret_from_fork+0x10/0x20 Code: d503201f f9416800 d503233f d50323bf (f9404c00) —[ end trace 0000000000000000 ]— Kernel panic - not syncing: Oops: Fatal exception in interrupt

This appears to be reproducible when the board has a fixed IP address, is ping flooded from another host, and reboot -f is used.

The following is one more manifestation of the issue:

$ reboot -f kvm: exiting hardware virtualization cfg80211: failed to load regulatory.db arm-smmu 5000000.iommu: disabling translation sdhci-esdhc 2140000.mmc: Removing from iommu group 11 sdhci-esdhc 2150000.mmc: Removing from iommu group 12 fsl-edma 22c0000.dma-controller: Removing from iommu group 17 dwc3 3100000.usb: Removing from iommu group 9 dwc3 3110000.usb: Removing from iommu group 10 ahci-qoriq 3200000.sata: Removing from iommu group 2 fsl-qdma 8380000.dma-controller: Removing from iommu group 20 platform f080000.display: Removing from iommu group 0 etnaviv-gpu f0c0000.gpu: Removing from iommu group 1 etnaviv etnaviv: Removing from iommu group 1 caam_jr 8010000.jr: Removing from iommu group 13 caam_jr 8020000.jr: Removing from iommu group 14 caam_jr 8030000.jr: Removing from iommu group 15 caam_jr 8040000.jr: Removing from iommu group 16 fsl_enetc 0000:00:00.0: Removing from iommu group 4 arm-smmu 5000000.iommu: Blocked unknown Stream ID 0x429; boot with arm-smmu.disable_bypass=0 to allow, but this may have security implications arm-smmu 5000000.iommu: GFSR 0x80000002, GFSYNR0 0x00000002, GFSYNR1 0x00000429, GFSYNR2 0x00000000 fsl_enetc 0000:00:00.1: Removing from iommu group 5 arm-smmu 5000000.iommu: Blocked unknown Stream ID 0x429; boot with arm-smmu.disable_bypass=0 to allow, but this may have security implications arm-smmu 5000000.iommu: GFSR 0x80000002, GFSYNR0 0x00000002, GFSYNR1 0x00000429, GFSYNR2 0x00000000 arm-smmu 5000000.iommu: Blocked unknown Stream ID 0x429; boot with arm-smmu.disable_bypass=0 to allow, but this may have security implications arm-smmu 5000000.iommu: GFSR 0x80000002, GFSYNR0 0x00000000, GFSYNR1 0x00000429, GFSYNR2 0x00000000 fsl_enetc 0000:00:00.2: Removing from iommu group 6 fsl_enetc_mdio 0000:00:00.3: Removing from iommu group 8 mscc_felix 0000:00:00.5: Removing from iommu group 3 fsl_enetc 0000:00:00.6: Removing from iommu group 7 pcieport 0001:00:00.0: Removing from iommu group 18 arm-smmu 5000000.iommu: Blocked unknown Stream ID 0x429; boot with arm-smmu.disable_bypass=0 to allow, but this may have security implications arm-smmu 5000000.iommu: GFSR 0x00000002, GFSYNR0 0x00000000, GFSYNR1 0x00000429, GFSYNR2 0x00000000 pcieport 0002:00:00.0: Removing from iommu group 19 Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a8 pc : iommu_get_dma_domain+0x14/0x20 lr : iommu_dma_unmap_page+0x38/0xe0 Call trace: iommu_get_dma_domain+0x14/0x20 dma_unmap_page_attrs+0x38/0x1d0 en —truncated—

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/a1b9c7b1978aacf4b2f33e34bde1e2bb80b8497a
• https://git.kernel.org/stable/c/ce31e6ca68bd7639bd3e5ef97be215031842bbab