Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: memcg: protect concurrent access to mem_cgroup_idr Commit 73f576c04b94 ("mm: memcontrol: fix cgroup creation failure after many small jobs") decoupled the memcg IDs from the CSS ID space to fix the cgroup creation failures. It introduced IDR to maintain the memcg ID space. The IDR depends on external synchronization mechanisms for modifications. For the mem_cgroup_idr, the idr_alloc() and idr_replace() happen within css callback and thus are protected through cgroup_mutex from concurrent modifications. However idr_remove() for mem_cgroup_idr was not protected against concurrency and can be run concurrently for different memcgs when they hit their refcnt to zero. Fix that. We have been seeing list_lru based kernel crashes at a low frequency in our fleet for a long time. These crashes were in different part of list_lru code including list_lru_add(), list_lru_del() and reparenting code. Upon further inspection, it looked like for a given object (dentry and inode), the super_block's list_lru didn't have list_lru_one for the memcg of that object. The initial suspicions were either the object is not allocated through kmem_cache_alloc_lru() or somehow memcg_list_lru_alloc() failed to allocate list_lru_one() for a memcg but returned success. No evidence were found for these cases. Looking more deeply, we started seeing situations where valid memcg's id is not present in mem_cgroup_idr and in some cases multiple valid memcgs have same id and mem_cgroup_idr is pointing to one of them. So, the most reasonable explanation is that these situations can happen due to race between multiple idr_remove() calls or race between idr_alloc()/idr_replace() and idr_remove(). These races are causing multiple memcgs to acquire the same ID and then offlining of one of them would cleanup list_lrus on the system for all of them. Later access from other memcgs to the list_lru cause crashes due to missing list_lru_one.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 73f576c04b9410ed19660f74f97521bee6e1c546 before 912736a0435ef40e6a4ae78197ccb5553cb80b05; affected 73f576c04b9410ed19660f74f97521bee6e1c546 before e6cc9ff2ac0b5df9f25eb790934c3104f6710278; affected 73f576c04b9410ed19660f74f97521bee6e1c546 before 56fd70f4aa8b82199dbe7e99366b1fd7a04d86fb; affected 73f576c04b9410ed19660f74f97521bee6e1c546 before 37a060b64ae83b76600d187d76591ce488ab836b; affected 73f576c04b9410ed19660f74f97521bee6e1c546 before 51c0b1bb7541f8893ec1accba59eb04361a70946; affected 73f576c04b9410ed19660f74f97521bee6e1c546 before 9972605a238339b85bd16b084eed5f18414d22db; affected 8627c7750a66a46d56d3564e1e881aa53764497c; affected db70cd18d3da727a3a59694de428a9e41c620de7; affected 4.4.18 before 4.5; affected 4.6.6 before 4.7 |
| Linux / Linux | affected 4.7; unaffected 0 before 4.7; unaffected 5.10.226 through 5.10.*; unaffected 5.15.167 through 5.15.*; unaffected 6.1.110 through 6.1.*; unaffected 6.6.46 through 6.6.*; unaffected 6.10.5 through 6.10.*; unaffected 6.11 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/912736a0435ef40e6a4ae78197ccb5553cb80b05
- https://git.kernel.org/stable/c/e6cc9ff2ac0b5df9f25eb790934c3104f6710278
- https://git.kernel.org/stable/c/56fd70f4aa8b82199dbe7e99366b1fd7a04d86fb
- https://git.kernel.org/stable/c/37a060b64ae83b76600d187d76591ce488ab836b
- https://git.kernel.org/stable/c/51c0b1bb7541f8893ec1accba59eb04361a70946
- https://git.kernel.org/stable/c/9972605a238339b85bd16b084eed5f18414d22db
ADP enrichment
No English description supplied.
No references supplied.
No English description supplied.