Description
In the Linux kernel, the following vulnerability has been resolved:
crypto: zstd - fix double-free in per-CPU stream cleanup
The crypto/zstd module has a double-free bug that occurs when multiple tfms are allocated and freed.
The issue happens because zstd_streams (per-CPU contexts) are freed in zstd_exit() during every tfm destruction, rather than being managed at the module level. When multiple tfms exist, each tfm exit attempts to free the same shared per-CPU streams, resulting in a double-free.
This leads to a stack trace similar to:
BUG: Bad page state in process kworker/u16:1 pfn:106fd93 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x106fd93 flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 0017ffffc0000000 dead000000000100 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: nonzero entire_mapcount Modules linked in: ... CPU: 3 UID: 0 PID: 2506 Comm: kworker/u16:1 Kdump: loaded Tainted: G B Hardware name: ... Workqueue: btrfs-delalloc btrfs_work_helper Call Trace: <TASK> dump_stack_lvl+0x5d/0x80 bad_page+0x71/0xd0 free_unref_page_prepare+0x24e/0x490 free_unref_page+0x60/0x170 crypto_acomp_free_streams+0x5d/0xc0 crypto_acomp_exit_tfm+0x23/0x50 crypto_destroy_tfm+0x60/0xc0 ...
Change the lifecycle management of zstd_streams to free the streams only once during module cleanup.
Metrics
No CVSS score has been published yet.
Affected software
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | >= f5ad93ffb54119a8dc5e18f070624d4ead586969, < dc0f4509b0ed5d82bef78e058db0ac4df04d0695; >= f5ad93ffb54119a8dc5e18f070624d4ead586969, < e983feaa79de1e46c9087fb9f02fedb0e5397ce6; >= f5ad93ffb54119a8dc5e18f070624d4ead586969, < 48bc9da3c97c15f1ea24934bcb3b736acd30163d |
| Linux | Linux | 6.17 |
References
Timeline
- Published
- Dec 16, 2025
- Last modified
- Oct 14, 2026
- NVD status
- Deferred