Description
In the Linux kernel, the following vulnerability has been resolved: mm: memcg: stop reclaim when a limit update is superseded kernfs serializes file operations only per open file, so separate open files can update the same memory.high or memory.max file concurrently. Both handlers store the new limit before synchronous reclaim, but continue to use the writer's local target in the reclaim loop. If another writer raises or removes the limit, the first writer can continue reclaiming toward a stale target. For memory.max, this can leave the writer looping indefinitely once reclaim retries are exhausted. The OOM path sees sufficient margin under the current limit and returns true without killing, while the writer still compares usage against its stale target and records another OOM event. Check the current limit at the start of each reclaim iteration and stop if it no longer matches the writer's target. Reproducer: Populate a cgroup with anonymous memory and disable swapping. Lower memory.max from one open file, then restore it to "max" through another open file after the new limit becomes visible. Without the patch, the first writer remains blocked and repeatedly increments the OOM event counter. With the patch, it returns normally. This was not motivated by a reported production workload. We found it through automated randomized testing for our cgroup observability work and reduced it to the reproducer above.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < ebf762a393630d1582645be3f0fc22a674eb9122affectedb6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < 4ea0617b9e46d26c0a3e5af00308ea1931cc545daffectedb6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < 5c6f87d33733d96fba66ea4e78cd8b24b4d60a49affectedb6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < 8bf21ad3657305e28deafd9ef16a121407496bc3affectedb6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < 39ec1e4183a718f448b2e9de681dcbdda18fce42affectedb6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < 95d87030cae7764805aa7c621c52871139297cb0affectedb6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < aab391074de96ed601eeca32daef9a8507d436d9affectedb6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f to < 9477820c63cbf4d97114238f3d1ff10dfd6bee3faffected0ccab5b139971a2a3f48df24d1ee8be2dbf84042affected97729c37439040ec07807f0dbb71ea60ccbafd27affected4.4.7 to < 4.5affected4.5.1 to < 4.6affected
Linux Linux
Default version status: affected
4.6affected0 to < 4.6unaffected5.10.270 to ≤ 5.10.*unaffected5.15.221 to ≤ 5.15.*unaffected6.1.188 to ≤ 6.1.*unaffected6.6.157 to ≤ 6.6.*unaffected6.12.109 to ≤ 6.12.*unaffected6.18.50 to ≤ 6.18.*unaffected7.2.4 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/ebf762a393630d1582645be3f0fc22a674eb9122 ↗
- https://git.kernel.org/stable/c/4ea0617b9e46d26c0a3e5af00308ea1931cc545d ↗
- https://git.kernel.org/stable/c/5c6f87d33733d96fba66ea4e78cd8b24b4d60a49 ↗
- https://git.kernel.org/stable/c/8bf21ad3657305e28deafd9ef16a121407496bc3 ↗
- https://git.kernel.org/stable/c/39ec1e4183a718f448b2e9de681dcbdda18fce42 ↗
- https://git.kernel.org/stable/c/95d87030cae7764805aa7c621c52871139297cb0 ↗
- https://git.kernel.org/stable/c/aab391074de96ed601eeca32daef9a8507d436d9 ↗
- https://git.kernel.org/stable/c/9477820c63cbf4d97114238f3d1ff10dfd6bee3f ↗