In the Linux kernel, the following vulnerability has been resolved: samples/damon/mtier: fail early if address range parameters are invalid

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

samples/damon/mtier: fail early if address range parameters are invalid

The comment on top of struct damon_region clearly says that

 1For any use case, @ar should be non-zero positive size.

which is now verified in damon_verify_new_region() if the kernel is built
with DAMON_DEBUG_SANITY.

The WARN_ONCE() can be triggered if the mtier sample module is enabled
before node{0,1}_{start,end}_addr have been properly initialized, which is
obviously not good.

------------[ cut here ]------------
start 0 >= end 0
WARNING: mm/damon/core.c:217 at damon_new_region+0xf4/0x118, CPU#59: bash/341468
Call trace:
damon_new_region+0xf4/0x118 (P)
damon_set_regions+0xfc/0x3c0
damon_sample_mtier_build_ctx+0xe8/0x3a8
damon_sample_mtier_start+0x1c/0x90
damon_sample_mtier_enable_store+0x98/0xb0
param_attr_store+0xb4/0x128
module_attr_store+0x2c/0x50
sysfs_kf_write+0x58/0x90
kernfs_fop_write_iter+0x16c/0x238
vfs_write+0x2c0/0x370
ksys_write+0x74/0x118
__arm64_sys_write+0x24/0x38
invoke_syscall+0xa8/0x118
el0_svc_common.constprop.0+0x48/0xf0
do_el0_svc+0x24/0x38
el0_svc+0x54/0x370
el0t_64_sync_handler+0xa0/0xe8
el0t_64_sync+0x1ac/0x1b0
---[ end trace 0000000000000000 ]---

Note that the same issue can happen if detect_node_addresses is true, and
node 0 or 1 is memoryless. Fix it together by checking the validity of
parameters right before damon_new_region() and fail early if they're
invalid.