CVE-2021-46906

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

HID: usbhid: fix info leak in hid_submit_ctrl

In hid_submit_ctrl(), the way of calculating the report length doesnt take into account that report->size can be zero. When running the syzkaller reproducer, a report of size 0 causes hid_submit_ctrl) to calculate transfer_buffer_length as 16384. When this urb is passed to the usb core layer, KMSAN reports an info leak of 16384 bytes.

To fix this, first modify hid_report_len() to account for the zero report size case by using DIV_ROUND_UP for the division. Then, call it from hid_submit_ctrl().

Weakness

The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource.

Affected Software

Extended Description

Resources such as files and directories may be inadvertently exposed through mechanisms such as insecure permissions, or when a program accidentally operates on the wrong object. For example, a program may intend that private files can only be provided to a specific user. This effectively defines a control sphere that is intended to prevent attackers from accessing these private files. If the file permissions are insecure, then parties other than the user will be able to access those files. A separate control sphere might effectively require that the user can only access the private files, but not any other files on the system. If the program does not ensure that the user is only requesting private files, then the user might be able to access other files on the system. In either case, the end result is that a resource has been exposed to the wrong party.

References

• https://git.kernel.org/stable/c/0e280502be1b003c3483ae03fc60dea554fcfa82
• https://git.kernel.org/stable/c/21883bff0fd854e07429a773ff18f1e9658f50e8
• https://git.kernel.org/stable/c/41b1e71a2c57366b08dcca1a28b0d45ca69429ce
• https://git.kernel.org/stable/c/6be388f4a35d2ce5ef7dbf635a8964a5da7f799f
• https://git.kernel.org/stable/c/7f5a4b24cdbd7372770a02f23e347d7d9a9ac8f1
• https://git.kernel.org/stable/c/8c064eece9a51856f3f275104520c7e3017fc5c0
• https://git.kernel.org/stable/c/b1e3596416d74ce95cc0b7b38472329a3818f8a9
• https://git.kernel.org/stable/c/c5d3c142f2d57d40c55e65d5622d319125a45366