CVE-2021-47272
Linux USB DWC3 Gadget NULL Pointer Dereference Vulnerability
Description
In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: gadget: Bail from dwc3_gadget_exit() if dwc->gadget is NULL There exists a possible scenario in which dwc3_gadget_init() can fail: during during host -> peripheral mode switch in dwc3_set_mode(), and a pending gadget driver fails to bind. Then, if the DRD undergoes another mode switch from peripheral->host the resulting dwc3_gadget_exit() will attempt to reference an invalid and dangling dwc->gadget pointer as well as call dma_free_coherent() on unmapped DMA pointers. The exact scenario can be reproduced as follows: - Start DWC3 in peripheral mode - Configure ConfigFS gadget with FunctionFS instance (or use g_ffs) - Run FunctionFS userspace application (open EPs, write descriptors, etc) - Bind gadget driver to DWC3's UDC - Switch DWC3 to host mode => dwc3_gadget_exit() is called. usb_del_gadget() will put the ConfigFS driver instance on the gadget_driver_pending_list - Stop FunctionFS application (closes the ep files) - Switch DWC3 to peripheral mode => dwc3_gadget_init() fails as usb_add_gadget() calls check_pending_gadget_drivers() and attempts to rebind the UDC to the ConfigFS gadget but fails with -19 (-ENODEV) because the FFS instance is not in FFS_ACTIVE state (userspace has not re-opened and written the descriptors yet, i.e. desc_ready!=0). - Switch DWC3 back to host mode => dwc3_gadget_exit() is called again, but this time dwc->gadget is invalid. Although it can be argued that userspace should take responsibility for ensuring that the FunctionFS application be ready prior to allowing the composite driver bind to the UDC, failure to do so should not result in a panic from the kernel driver. Fix this by setting dwc->gadget to NULL in the failure path of dwc3_gadget_init() and add a check to dwc3_gadget_exit() to bail out unless the gadget pointer is valid.
INFO
Published Date :
May 21, 2024, 3:15 p.m.
Last Modified :
May 21, 2024, 4:54 p.m.
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Remotely Exploitable :
No
Impact Score :
Exploitability Score :
References to Advisories, Solutions, and Tools
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CVE-2021-47272
vulnerability anywhere in the article.
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CVE-2021-47272
vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 28, 2024
Action Type Old Value New Value -
CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 21, 2024
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: gadget: Bail from dwc3_gadget_exit() if dwc->gadget is NULL There exists a possible scenario in which dwc3_gadget_init() can fail: during during host -> peripheral mode switch in dwc3_set_mode(), and a pending gadget driver fails to bind. Then, if the DRD undergoes another mode switch from peripheral->host the resulting dwc3_gadget_exit() will attempt to reference an invalid and dangling dwc->gadget pointer as well as call dma_free_coherent() on unmapped DMA pointers. The exact scenario can be reproduced as follows: - Start DWC3 in peripheral mode - Configure ConfigFS gadget with FunctionFS instance (or use g_ffs) - Run FunctionFS userspace application (open EPs, write descriptors, etc) - Bind gadget driver to DWC3's UDC - Switch DWC3 to host mode => dwc3_gadget_exit() is called. usb_del_gadget() will put the ConfigFS driver instance on the gadget_driver_pending_list - Stop FunctionFS application (closes the ep files) - Switch DWC3 to peripheral mode => dwc3_gadget_init() fails as usb_add_gadget() calls check_pending_gadget_drivers() and attempts to rebind the UDC to the ConfigFS gadget but fails with -19 (-ENODEV) because the FFS instance is not in FFS_ACTIVE state (userspace has not re-opened and written the descriptors yet, i.e. desc_ready!=0). - Switch DWC3 back to host mode => dwc3_gadget_exit() is called again, but this time dwc->gadget is invalid. Although it can be argued that userspace should take responsibility for ensuring that the FunctionFS application be ready prior to allowing the composite driver bind to the UDC, failure to do so should not result in a panic from the kernel driver. Fix this by setting dwc->gadget to NULL in the failure path of dwc3_gadget_init() and add a check to dwc3_gadget_exit() to bail out unless the gadget pointer is valid. Added Reference kernel.org https://git.kernel.org/stable/c/851dee5a5da56564a70290713aee665403bb0b24 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/4aad390363d2b9b3e92428dd34d27bb7ea8f1ee8 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/03715ea2e3dbbc56947137ce3b4ac18a726b2f87 [No types assigned]
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-47272
is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-47272
weaknesses.