Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: btrfs: zstd: fix lost wakeup when waiting for a workspace A writer can sleep forever in zstd_get_workspace() even though a workspace is free. When zstd_alloc_workspace() fails, the task is queued on zwsm->wait and schedules unconditionally, never re-testing the pool. zstd_put_workspace() publishes the workspace and then calls cond_wake_up(), which only wakes when a sleeper is already visible, so a workspace returned between the failed allocation and prepare_to_wait() wakes nobody. The window is wide: zstd_alloc_workspace() goes through kvmalloc() and may enter reclaim. Only a max level workspace triggers the wakeup and one is deliberately kept allocated as the fallback every waiter waits for, so once its wakeup is lost the writer stays in TASK_UNINTERRUPTIBLE until some other task happens to return one. Re-check the pool after prepare_to_wait() has published the waiter, and use the workspace if one turned up.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 before 14d982762945d9945c60bbd48b77df194dd8e28d; affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 before 844603cf842ee67640d33f350e3fa60f3de7fad3; affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 before d8f57049521948df5f50797141472fbbed3b0723; affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 before 0de9f31d447ae71ab08c7850a321682f8d2907c3; affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 before 2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7 |
| Linux / Linux | affected 5.1; unaffected 0 before 5.1; unaffected 6.6.160 through 6.6.*; unaffected 6.12.114 through 6.12.*; unaffected 6.18.53 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/14d982762945d9945c60bbd48b77df194dd8e28d
- https://git.kernel.org/stable/c/844603cf842ee67640d33f350e3fa60f3de7fad3
- https://git.kernel.org/stable/c/d8f57049521948df5f50797141472fbbed3b0723
- https://git.kernel.org/stable/c/0de9f31d447ae71ab08c7850a321682f8d2907c3
- https://git.kernel.org/stable/c/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7