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 dont 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.
References
- https://git.kernel.org/stable/c/1292c0ecb1caefb8ca064a3639d5673991e8810c
- https://git.kernel.org/stable/c/43aaddd0fa92010a68adeda7744c7cf497a1c8e9
- https://git.kernel.org/stable/c/4b6f1d6d5d07855bd1bb9e64922b049062138bfa
- https://git.kernel.org/stable/c/b585facbafbb5cf117b37b1c75819ac046646c27
- https://git.kernel.org/stable/c/c927b73a5694c735314ea10e7c81c07f9bd51ad7