Linux Kernel RCU Protection Vulnerability in Disk Zone Management

A vulnerability in the Linux kernel's handling of disk zone management has been addressed. The issue arose from improper management of the conventional zones bitmap during disk revalidation, which could lead to invalid memory references. This vulnerability has been mitigated by implementing RCU protection for the disk's conventional zones bitmap pointer. The helper function 'disk_zone_is_conv()' has been updated to operate under the RCU read lock, and a new function, 'disk_set_conv_zones_bitmap()', has been introduced to safely update the conventional zones bitmap pointer using 'rcu_replace_pointer()' while holding the 'disk_zone_wplugs_lock' spinlock. Additionally, 'disk_free_zone_resources()' has been modified to call 'disk_update_zone_resources()' with a NULL bitmap pointer to release the conventional zones bitmap. The 'disk_set_conv_zones_bitmap()' function is also utilized in 'disk_update_zone_resources()' to apply the new (revalidated) bitmap and free the previous one.

Impact

Exploitation of this vulnerability could lead to invalid memory references, potentially causing memory corruption or other unintended behavior in the kernel.