CVE-2024-50121

Summary

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.

Affected Software

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: total

CVE Program Container

Additional References

• https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
• https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html

Additional References

• https://cert-portal.siemens.com/productcert/html/ssa-265688.html

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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