Linux Kernel up to 5.12.10 usb_assign_descriptors null pointer dereference

Summaryinfo

A vulnerability has been found in Linux Kernel up to 5.12.10 and classified as critical. The impacted element is the function usb_assign_descriptors. This manipulation causes null pointer dereference. This vulnerability appears as CVE-2021-47267. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.12.10. It has been declared as critical. Affected by this vulnerability is the function usb_assign_descriptors. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. 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. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: usb: fix various gadget panics on 10gbps cabling usb_assign_descriptors() is called with 5 parameters, the last 4 of which are the usb_descriptor_header for: full-speed (USB1.1 - 12Mbps [including USB1.0 low-speed @ 1.5Mbps), high-speed (USB2.0 - 480Mbps), super-speed (USB3.0 - 5Gbps), super-speed-plus (USB3.1 - 10Gbps). The differences between full/high/super-speed descriptors are usually substantial (due to changes in the maximum usb block size from 64 to 512 to 1024 bytes and other differences in the specs), while the difference between 5 and 10Gbps descriptors may be as little as nothing (in many cases the same tuning is simply good enough). However if a gadget driver calls usb_assign_descriptors() with a NULL descriptor for super-speed-plus and is then used on a max 10gbps configuration, the kernel will crash with a null pointer dereference, when a 10gbps capable device port + cable + host port combination shows up. (This wouldn't happen if the gadget max-speed was set to 5gbps, but it of course defaults to the maximum, and there's no real reason to artificially limit it) The fix is to simply use the 5gbps descriptor as the 10gbps descriptor, if a 10gbps descriptor wasn't provided. Obviously this won't fix the problem if the 5gbps descriptor is also NULL, but such cases can't be so trivially solved (and any such gadgets are unlikely to be used with USB3 ports any way).

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2021-47267 since 05/21/2024. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 4.9.273, 4.14.237, 4.19.195, 5.4.126, 5.10.44 or 5.12.11 eliminates this vulnerability. Applying the patch fd24be23abf3/70cd19cb5bd9/45f9a2fe737d/5ef23506695b/b972eff87463/ca6bc277430d/032e288097a5 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.9.272
• 4.14.236
• 4.19.194
• 5.4.125
• 5.10.0
• 5.10.1
• 5.10.2
• 5.10.3
• 5.10.4
• 5.10.5
• 5.10.6
• 5.10.7
• 5.10.8
• 5.10.9
• 5.10.10
• 5.10.11
• 5.10.12
• 5.10.13
• 5.10.14
• 5.10.15
• 5.10.16
• 5.10.17
• 5.10.18
• 5.10.19
• 5.10.20
• 5.10.21
• 5.10.22
• 5.10.23
• 5.10.24
• 5.10.25
• 5.10.26
• 5.10.27
• 5.10.28
• 5.10.29
• 5.10.30
• 5.10.31
• 5.10.32
• 5.10.33
• 5.10.34
• 5.10.35
• 5.10.36
• 5.10.37
• 5.10.38
• 5.10.39
• 5.10.40
• 5.10.41
• 5.10.42
• 5.10.43
• 5.12.0
• 5.12.1
• 5.12.2
• 5.12.3
• 5.12.4
• 5.12.5
• 5.12.6
• 5.12.7
• 5.12.8
• 5.12.9
• 5.12.10

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

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