About vulnerability

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

mm/damon/core: validate ranges in damon_set_regions()

DAMON core logic assumes zero length regions don’t exist. However, a few DAMON API callers including DAMON_SYSFS, DAMON_RECLAIM and DAMON_LRU_SORT allow users to set empty monitoring target regions. This could result in WARN_ONCE() on CONFIG_DAMON_DEBUG_SANITY enabled kernel, and divide-by-zero from damon_merge_two_regions().

For example, the WANR_ONCE() can be triggered like below.

grep DAMON_DEBUG_SANITY /boot/config-$(uname -r)

CONFIG_DAMON_DEBUG_SANITY=y

damo start

cd /sys/kernel/mm/damon/admin/kdamonds/0

echo 0 > contexts/0/targets/0/regions/0/start

echo 0 > contexts/0/targets/0/regions/0/end

echo commit > state

dmesg

[….] [ 73.705780] ————[ cut here ]———— [ 73.707552] start 0 >= end 0 [ 73.708452] WARNING: mm/damon/core.c:359 at damon_new_region+0x6e/0x80, CPU#1: kdamond.0/758 […]

All DAMON API callers eventually use damon_set_regions() to setup the regions. Add the validation logic in the function.

Affected product:

AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Debian 10 ELS , TuxCare 9.6 ESU

Affected packages:

kernel @ 5.14.0 (+5 more)