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Vulnerability CVE-2024-35846
Published: 2024-05-17
| Description: |
In the Linux kernel, the following vulnerability has been resolved:
mm: zswap: fix shrinker NULL crash with cgroup_disable=memory
Christian reports a NULL deref in zswap that he bisected down to the zswap
shrinker. The issue also cropped up in the bug trackers of libguestfs [1]
and the Red Hat bugzilla [2].
The problem is that when memcg is disabled with the boot time flag, the
zswap shrinker might get called with sc->memcg == NULL. This is okay in
many places, like the lruvec operations. But it crashes in
memcg_page_state() - which is only used due to the non-node accounting of
cgroup's the zswap memory to begin with.
Nhat spotted that the memcg can be NULL in the memcg-disabled case, and I
was then able to reproduce the crash locally as well.
[1] https://github.com/libguestfs/libguestfs/issues/139
[2] https://bugzilla.redhat.com/show_bug.cgi?id=2275252 |
References: |
https://git.kernel.org/stable/c/b0fdabc908a7f81d12382c87ca9e46a9c2e14042
https://git.kernel.org/stable/c/682886ec69d22363819a83ddddd5d66cb5c791e1
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