UBUNTU-CVE-2026-74643: Medium severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: samples/damon/mtier: error out for zero quota goal target values Patch series "mm/damon: avoid division by zero from damosquotascore()". DAMONSAMPLEMTIER and DAMONLRUSORT allow the user to trigger division by zero in damosquotascore(). Avoid it by adding parameters validation checks. This patch (of 2): damosquotascore() can trigger division by zero if the targetvalue is zero. DAMONSAMPLEMTIER lets users set the targetvalue via node0mem{used,free}bp parameters. It doesn't guard zero value case, though. As a result, users can trigger division by zero. Fix the issue by returning an error when the user tries to start DAMON with zero node0mem{used,free}bp parameter values. DAMONSAMPLEMTIER is just a sample module, but the consequence is quite bad. Also the zero node0memfreebp parameter might look like a reasonable setup to some users. Hence, the issue might really happen in the real world. One reliable way to reproduce the issue is like below: # cd /sys/module/damonsamplemtier/parameters # echo 4096 > node0startaddr # echo 8192 > node0endaddr # echo 8192 > node1startaddr # echo 81920 > node1endaddr # echo 0 > node0memfreebp # echo Y > enabled # dmesg -w [...] [18792.235916] Oops: divide error: 0000 [#1] SMP NOPTI [...] [18792.242787] RIP: 0010:damosquotascore+0x6f/0x480 [...] This issue was discovered [1] by Sashiko.