CVE-2026-80592

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

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

which is now verified in damonverifynewregion() if the kernel is built with DAMONDEBUG_SANITY.

The WARNONCE() 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 damonnewregion+0xf4/0x118, CPU#59: bash/341468 Call trace: damonnewregion+0xf4/0x118 (P) damonsetregions+0xfc/0x3c0 damonsamplemtierbuildctx+0xe8/0x3a8 damonsamplemtierstart+0x1c/0x90 damonsamplemtierenablestore+0x98/0xb0 paramattrstore+0xb4/0x128 moduleattrstore+0x2c/0x50 sysfskfwrite+0x58/0x90 kernfsfopwriteiter+0x16c/0x238 vfswrite+0x2c0/0x370 ksyswrite+0x74/0x118 _arm64syswrite+0x24/0x38 invokesyscall+0xa8/0x118 el0svccommon.constprop.0+0x48/0xf0 doel0svc+0x24/0x38 el0svc+0x54/0x370 el0t64synchandler+0xa0/0xe8 el0t64sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]---

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