CVE-2022-50133

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

usb: xhci_plat_remove: avoid NULL dereference

Since commit 4736ebd7fcaff1eb8481c140ba494962847d6e0a (usb: host: xhci-plat: omit shared hcd if either root hub has no ports) xhci->shared_hcd can be NULL, which causes the following Oops on reboot:

[ 710.124450] systemd-shutdown[1]: Rebooting. [ 710.298861] xhci-hcd xhci-hcd.2.auto: remove, state 4 [ 710.304217] usb usb3: USB disconnect, device number 1 [ 710.317441] xhci-hcd xhci-hcd.2.auto: USB bus 3 deregistered [ 710.323280] xhci-hcd xhci-hcd.2.auto: remove, state 1 [ 710.328401] usb usb2: USB disconnect, device number 1 [ 710.333515] usb 2-3: USB disconnect, device number 2 [ 710.467649] xhci-hcd xhci-hcd.2.auto: USB bus 2 deregistered [ 710.475450] Unable to handle kernel NULL pointer dereference at virtual address 00000000000003b8 [ 710.484425] Mem abort info: [ 710.487265] ESR = 0x0000000096000004 [ 710.491060] EC = 0x25: DABT (current EL), IL = 32 bits [ 710.496427] SET = 0, FnV = 0 [ 710.499525] EA = 0, S1PTW = 0 [ 710.502716] FSC = 0x04: level 0 translation fault [ 710.507648] Data abort info: [ 710.510577] ISV = 0, ISS = 0x00000004 [ 710.514462] CM = 0, WnR = 0 [ 710.517480] user pgtable: 4k pages, 48-bit VAs, pgdp=00000008b0050000 [ 710.523976] [00000000000003b8] pgd=0000000000000000, p4d=0000000000000000 [ 710.530961] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 710.536551] Modules linked in: rfkill input_leds snd_soc_simple_card snd_soc_simple_card_utils snd_soc_nau8822 designware_i2s snd_soc_core dw_hdmi_ahb_audio snd_pcm_dmaengine arm_ccn panfrost ac97_bus gpu_sched snd_pcm at24 fuse configfs sdhci_of_dwcmshc sdhci_pltfm sdhci nvme led_class mmc_core nvme_core bt1_pvt polynomial tp_serio snd_seq_midi snd_seq_midi_event snd_seq snd_timer snd_rawmidi snd_seq_device snd soundcore efivarfs ipv6 [ 710.575286] CPU: 7 PID: 1 Comm: systemd-shutdow Not tainted 5.19.0-rc7-00043-gfd8619f4fd54 #1 [ 710.583822] Hardware name: T-Platforms TF307-MB/BM1BM1-A, BIOS 5.6 07/06/2022 [ 710.590972] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=–) [ 710.597949] pc : usb_remove_hcd+0x34/0x1e4 [ 710.602067] lr : xhci_plat_remove+0x74/0x140 [ 710.606351] sp : ffff800009f3b7c0 [ 710.609674] x29: ffff800009f3b7c0 x28: ffff000800960040 x27: 0000000000000000 [ 710.616833] x26: ffff800008dc22a0 x25: 0000000000000000 x24: 0000000000000000 [ 710.623992] x23: 0000000000000000 x22: ffff000805465810 x21: ffff000805465800 [ 710.631149] x20: ffff000800f80000 x19: 0000000000000000 x18: ffffffffffffffff [ 710.638307] x17: ffff000805096000 x16: ffff00080633b800 x15: ffff000806537a1c [ 710.645465] x14: 0000000000000001 x13: 0000000000000000 x12: ffff00080378d6f0 [ 710.652621] x11: ffff00080041a900 x10: ffff800009b204e8 x9 : ffff8000088abaa4 [ 710.659779] x8 : ffff000800960040 x7 : ffff800009409000 x6 : 0000000000000001 [ 710.666936] x5 : ffff800009241000 x4 : ffff800009241440 x3 : 0000000000000000 [ 710.674094] x2 : ffff000800960040 x1 : ffff000800960040 x0 : 0000000000000000 [ 710.681251] Call trace: [ 710.683704] usb_remove_hcd+0x34/0x1e4 [ 710.687467] xhci_plat_remove+0x74/0x140 [ 710.691400] platform_remove+0x34/0x70 [ 710.695165] device_remove+0x54/0x90 [ 710.698753] device_release_driver_internal+0x200/0x270 [ 710.703992] device_release_driver+0x24/0x30 [ 710.708273] bus_remove_device+0xe0/0x16c [ 710.712293] device_del+0x178/0x390 [ 710.715797] platform_device_del.part.0+0x24/0x90 [ 710.720514] platform_device_unregister+0x30/0x50 [ 710.725232] dwc3_host_exit+0x20/0x30 [ 710.728907] dwc3_remove+0x174/0x1b0 [ 710.732494] platform_remove+0x34/0x70 [ 710.736254] device_remove+0x54/0x90 [ 710.739840] device_release_driver_internal+0x200/0x270 [ 710.745078] device_release_driver+0x24/0x30 [ 710.749359] bus_remove_device+0xe0/0x16c [ 710.753380] device_del+0x178/0x390 [ 710.756881] platform_device_del.part —truncated—

Weakness

The product dereferences a pointer that it expects to be valid but is NULL.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/371a8af4f26e06b4d51d893b4436f520b48d07fd
• https://git.kernel.org/stable/c/d7de14d74d6551f0d097430f9893ce82ad17e5b8