CVE-2021-47055: Improper Locking

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

mtd: require write permissions for locking and badblock ioctls

MEMLOCK, MEMUNLOCK and OTPLOCK modify protection bits. Thus require write permission. Depending on the hardware MEMLOCK might even be write-once, e.g. for SPI-NOR flashes with their WP# tied to GND. OTPLOCK is always write-once.

MEMSETBADBLOCK modifies the bad block table.