AZL-62633

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

block: RCU protect disk->convzonesbitmap

Ensure that a disk revalidation changing the conventional zones bitmap of a disk does not cause invalid memory references when using the diskzoneisconv() helper by RCU protecting the disk->convzones_bitmap pointer.

diskzoneisconv() is modified to operate under the RCU read lock and the function disksetconvzonesbitmap() is added to update a disk convzonesbitmap pointer using rcureplacepointer() with the disk zonewplugs_lock spinlock held.

diskfreezoneresources() is modified to call diskupdatezoneresources() with a NULL bitmap pointer to free the disk convzonesbitmap. disksetconvzonesbitmap() is also used in diskupdatezone_resources() to set the new (revalidated) bitmap and free the old one.