CVE-2026-74645

What the bug is

damos_quota_score() can trigger division by zero if the target value is zero. DAMON_LRU_SORT lets users set the target value for the hot memory scheme via active_mem_bp parameter. It avoids setting it as the target value if the parameter value is zero. However, it also sets the cold memory scheme with a target value that is calculated as '10000 - active_mem_bp + 2'. Hence, if a user sets active_mem_bp 10002, the cold memory scheme's quota goal target value can be zero. As a result, division by zero can be triggered. Fix by returning an error when the user tries to start DAMON with >10000 active_mem_bp parameter value. It makes no sense to set active_mem_bp with 10002. It also requires module parameters write permission to reproduce the issue. That said, the consequence is quite bad. One reliable way to reproduce the issue is like below: # cd /sys/module/damon_lru_sort/parameters # echo 1000 > wmarks_high # echo 995 > wmarks_mid # echo 0 > wmarks_low # echo 10002 > active_mem_bp # echo Y > enabled # dmesg -w [...] [ 597.421247] Oops: divide error: 0000 [#1] SMP NOPTI [ 597.428848] RIP: 0010:damos_quota_score+0x6f/0x480 This issue was discovered [1] by Sashiko.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

mm/damon/lru_sort.c

What this is

DAMONMAINTAINERS section matched on mm/damon/ · damon@lists.linux.dev · Maintained

Check it on the machine

grep -wE 'CONFIG_DAMON|CONFIG_DAMON_LRU_SORT' /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

Show whether Debian builds this, per release

Debian does not build this code in 1 release. It does build it in 3 releases, so the answer depends on which release the machine runs.

• bookwormn
• trixie, forky, sidy

n

not enabled on any flavour - this release does not build the code

y

built into the kernel image on every flavour - only a patch removes it

Build switches

CONFIG_DAMON, CONFIG_DAMON_LRU_SORT

Reads as

all on means the file is compiled; any one off means it is not.

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2026-08-22 (2 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.20%, higher than 8.9% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

mm/damon

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
7.0	7.1.9	e7e5e5e0dfe2
7.0	7.2	06befa61c427