In the Linux kernel, the following vulnerability has been resolved:
f2fs: use the mount idmap for the owner check in f2fs_xattr_advise_set()
f2fs_xattr_advise_set() calls inode_owner_or_capable() with &nop_mnt_idmap
before allowing the “system.advise” xattr to be set, instead of the idmap
that the VFS passes to the ->set() handler.
f2fs supports idmapped mounts, so on such a mount this checks the caller’s
fsuid against the unmapped on-disk owner rather than the mapped owner: the
actual owner can be wrongly denied with -EPERM and an unrelated caller
wrongly allowed. Pass the handler’s idmap instead.
