Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: mm: memcg: stop reclaim when a limit update is superseded kernfs serializes file operations only per open file, so separate open files can update the same memory.high or memory.max file concurrently.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 (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before ebf762a393630d1582645be3f0fc22a674eb9122; affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before 4ea0617b9e46d26c0a3e5af00308ea1931cc545d; affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before 5c6f87d33733d96fba66ea4e78cd8b24b4d60a49; affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before 8bf21ad3657305e28deafd9ef16a121407496bc3; affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before 39ec1e4183a718f448b2e9de681dcbdda18fce42; affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before 95d87030cae7764805aa7c621c52871139297cb0; affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before aab391074de96ed601eeca32daef9a8507d436d9; affected b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f before 9477820c63cbf4d97114238f3d1ff10dfd6bee3f; affected 0ccab5b139971a2a3f48df24d1ee8be2dbf84042; affected 97729c37439040ec07807f0dbb71ea60ccbafd27; affected 4.4.7 before 4.5; affected 4.5.1 before 4.6 |
| Linux / Linux | affected 4.6; unaffected 0 before 4.6; unaffected 5.10.270 through 5.10.*; unaffected 5.15.221 through 5.15.*; unaffected 6.1.188 through 6.1.*; unaffected 6.6.157 through 6.6.*; unaffected 6.12.109 through 6.12.*; unaffected 6.18.50 through 6.18.*; unaffected 7.2.4 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.
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