CVE-2022-50551

Description

From CVE.org

In the Linux kernel, the following vulnerability has been resolved: wifi: brcmfmac: Fix potential shift-out-of-bounds in brcmf_fw_alloc_request() This patch fixes a shift-out-of-bounds in brcmfmac that occurs in BIT(chiprev) when a 'chiprev' provided by the device is too large. It should also not be equal to or greater than BITS_PER_TYPE(u32) as we do bitwise AND with a u32 variable and BIT(chiprev). The patch adds a check that makes the function return NULL if that is the case. Note that the NULL case is later handled by the bus-specific caller, brcmf_usb_probe_cb() or brcmf_usb_reset_resume(), for example. Found by a modified version of syzkaller. UBSAN: shift-out-of-bounds in drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c shift exponent 151055786 is too large for 64-bit type 'long unsigned int' CPU: 0 PID: 1885 Comm: kworker/0:2 Tainted: G O 5.14.0+ #132 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 Workqueue: usb_hub_wq hub_event Call Trace: dump_stack_lvl+0x57/0x7d ubsan_epilogue+0x5/0x40 __ubsan_handle_shift_out_of_bounds.cold+0x53/0xdb ? lock_chain_count+0x20/0x20 brcmf_fw_alloc_request.cold+0x19/0x3ea ? brcmf_fw_get_firmwares+0x250/0x250 ? brcmf_usb_ioctl_resp_wait+0x1a7/0x1f0 brcmf_usb_get_fwname+0x114/0x1a0 ? brcmf_usb_reset_resume+0x120/0x120 ? number+0x6c4/0x9a0 brcmf_c_process_clm_blob+0x168/0x590 ? put_dec+0x90/0x90 ? enable_ptr_key_workfn+0x20/0x20 ? brcmf_common_pd_remove+0x50/0x50 ? rcu_read_lock_sched_held+0xa1/0xd0 brcmf_c_preinit_dcmds+0x673/0xc40 ? brcmf_c_set_joinpref_default+0x100/0x100 ? rcu_read_lock_sched_held+0xa1/0xd0 ? rcu_read_lock_bh_held+0xb0/0xb0 ? lock_acquire+0x19d/0x4e0 ? find_held_lock+0x2d/0x110 ? brcmf_usb_deq+0x1cc/0x260 ? mark_held_locks+0x9f/0xe0 ? lockdep_hardirqs_on_prepare+0x273/0x3e0 ? _raw_spin_unlock_irqrestore+0x47/0x50 ? trace_hardirqs_on+0x1c/0x120 ? brcmf_usb_deq+0x1a7/0x260 ? brcmf_usb_rx_fill_all+0x5a/0xf0 brcmf_attach+0x246/0xd40 ? wiphy_new_nm+0x1476/0x1d50 ? kmemdup+0x30/0x40 brcmf_usb_probe+0x12de/0x1690 ? brcmf_usbdev_qinit.constprop.0+0x470/0x470 usb_probe_interface+0x25f/0x710 really_probe+0x1be/0xa90 __driver_probe_device+0x2ab/0x460 ? usb_match_id.part.0+0x88/0xc0 driver_probe_device+0x49/0x120 __device_attach_driver+0x18a/0x250 ? driver_allows_async_probing+0x120/0x120 bus_for_each_drv+0x123/0x1a0 ? bus_rescan_devices+0x20/0x20 ? lockdep_hardirqs_on_prepare+0x273/0x3e0 ? trace_hardirqs_on+0x1c/0x120 __device_attach+0x207/0x330 ? device_bind_driver+0xb0/0xb0 ? kobject_uevent_env+0x230/0x12c0 bus_probe_device+0x1a2/0x260 device_add+0xa61/0x1ce0 ? __mutex_unlock_slowpath+0xe7/0x660 ? __fw_devlink_link_to_suppliers+0x550/0x550 usb_set_configuration+0x984/0x1770 ? kernfs_create_link+0x175/0x230 usb_generic_driver_probe+0x69/0x90 usb_probe_device+0x9c/0x220 really_probe+0x1be/0xa90 __driver_probe_device+0x2ab/0x460 driver_probe_device+0x49/0x120 __device_attach_driver+0x18a/0x250 ? driver_allows_async_probing+0x120/0x120 bus_for_each_drv+0x123/0x1a0 ? bus_rescan_devices+0x20/0x20 ? lockdep_hardirqs_on_prepare+0x273/0x3e0 ? trace_hardirqs_on+0x1c/0x120 __device_attach+0x207/0x330 ? device_bind_driver+0xb0/0xb0 ? kobject_uevent_env+0x230/0x12c0 bus_probe_device+0x1a2/0x260 device_add+0xa61/0x1ce0 ? __fw_devlink_link_to_suppliers+0x550/0x550 usb_new_device.cold+0x463/0xf66 ? hub_disconnect+0x400/0x400 ? _raw_spin_unlock_irq+0x24/0x30 hub_event+0x10d5/0x3330 ? hub_port_debounce+0x280/0x280 ? __lock_acquire+0x1671/0x5790 ? wq_calc_node_cpumask+0x170/0x2a0 ? lock_release+0x640/0x640 ? rcu_read_lock_sched_held+0xa1/0xd0 ? rcu_read_lock_bh_held+0xb0/0xb0 ? lockdep_hardirqs_on_prepare+0x273/0x3e0 process_one_work+0x873/0x13e0 ? lock_release+0x640/0x640 ? pwq_dec_nr_in_flight+0x320/0x320 ? rwlock_bug.part.0+0x90/0x90 worker_thread+0x8b/0xd10 ? __kthread_parkme+0xd9/0x1d0 ? pr ---truncated---

Statement

The patch prevents a shift-out-of-bounds in brcmf_fw_map_chip_to_name() (BIT(chiprev)) when a device reports an out-of-range chiprev, which could otherwise lead to undefined behavior and kernel crashes during driver probe. Impact is mostly DoS: it can be reproduced by attaching a malicious/buggy Broadcom USB/SDIO device (or USB emulator/gadget) that advertises an excessively large chiprev, triggering the UBSAN splat/panic during probe. For the CVSS the PR:H — exploitation requires control of the hardware/firmware or the ability to emulate/hot-plug a crafted device (or load/probe the driver).

Common Vulnerability Scoring System (CVSS) Score Details

Info alert:Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 Score Breakdown

Red HatNVDcve.org
Base Score6.27.1N/A
Attack VectorLocalLocalN/A
Attack ComplexityLowLowN/A
Privileges RequiredNoneLowN/A
User InteractionNoneNoneN/A
ScopeUnchangedUnchangedN/A
ConfidentialityNoneHighN/A
Integrity ImpactNoneNoneN/A
Availability ImpactHighHighN/A

Vector

Red Hat: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Understanding the Weakness (CWE)

CWE-682

Availability

Technical Impact: DoS: Crash, Exit, or Restart

If the incorrect calculation causes the program to move into an unexpected state, it may lead to a crash or impairment of service.

Integrity,Confidentiality,Availability

Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Other); Execute Unauthorized Code or Commands

If the incorrect calculation is used in the context of resource allocation, it could lead to an out-of-bounds operation (CWE-119) leading to a crash or even arbitrary code execution. Alternatively, it may result in an integer overflow (CWE-190) and / or a resource consumption problem (CWE-400).

Access Control

Technical Impact: Gain Privileges or Assume Identity

In the context of privilege or permissions assignment, an incorrect calculation can provide an attacker with access to sensitive resources.

Access Control

Technical Impact: Bypass Protection Mechanism

If the incorrect calculation leads to an insufficient comparison (CWE-697), it may compromise a protection mechanism such as a validation routine and allow an attacker to bypass the security-critical code.

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