CVE-2021-47173

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

misc/uss720: fix memory leak in uss720_probe

uss720_probe forgets to decrease the refcount of usbdev in uss720_probe. Fix this by decreasing the refcount of usbdev by usb_put_dev.

BUG: memory leak unreferenced object 0xffff888101113800 (size 2048): comm kworker/0:1, pid 7, jiffies 4294956777 (age 28.870s) hex dump (first 32 bytes): ff ff ff ff 31 00 00 00 00 00 00 00 00 00 00 00 ….1……….. 00 00 00 00 00 00 00 00 00 00 00 00 03 00 00 00 ……………. backtrace: [] kmalloc include/linux/slab.h:554 [inline] [] kzalloc include/linux/slab.h:684 [inline] [] usb_alloc_dev+0x32/0x450 drivers/usb/core/usb.c:582 [] hub_port_connect drivers/usb/core/hub.c:5129 [inline] [] hub_port_connect_change drivers/usb/core/hub.c:5363 [inline] [] port_event drivers/usb/core/hub.c:5509 [inline] [] hub_event+0x1171/0x20c0 drivers/usb/core/hub.c:5591 [] process_one_work+0x2c9/0x600 kernel/workqueue.c:2275 [] worker_thread+0x59/0x5d0 kernel/workqueue.c:2421 [] kthread+0x178/0x1b0 kernel/kthread.c:292 [] ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/36b5ff1db1a4ef4fdbc2bae364344279f033ad88
• https://git.kernel.org/stable/c/386918878ce4cd676e4607233866e03c9399a46a
• https://git.kernel.org/stable/c/5394ae9d8c7961dd93807fdf1b12a1dde96b0a55
• https://git.kernel.org/stable/c/5f46b2410db2c8f26b8bb91b40deebf4ec184391
• https://git.kernel.org/stable/c/7889c70e6173ef358f3cd7578db127a489035a42
• https://git.kernel.org/stable/c/a3c3face38cb49932c62adcc1289914f1c742096
• https://git.kernel.org/stable/c/bcb30cc8f8befcbdbcf7a016e4dfd4747c54a364
• https://git.kernel.org/stable/c/dcb4b8ad6a448532d8b681b5d1a7036210b622de