CVE-2022-50401
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-18

Last updated on: 2025-12-11

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: under NFSv4.1, fix double svc_xprt_put on rpc_create failure On error situation `clp->cl_cb_conn.cb_xprt` should not be given a reference to the xprt otherwise both client cleanup and the error handling path of the caller call to put it. Better to delay handing over the reference to a later branch. [ 72.530665] refcount_t: underflow; use-after-free. [ 72.531933] WARNING: CPU: 0 PID: 173 at lib/refcount.c:28 refcount_warn_saturate+0xcf/0x120 [ 72.533075] Modules linked in: nfsd(OE) nfsv4(OE) nfsv3(OE) nfs(OE) lockd(OE) compat_nfs_ssc(OE) nfs_acl(OE) rpcsec_gss_krb5(OE) auth_rpcgss(OE) rpcrdma(OE) dns_resolver fscache netfs grace rdma_cm iw_cm ib_cm sunrpc(OE) mlx5_ib mlx5_core mlxfw pci_hyperv_intf ib_uverbs ib_core xt_MASQUERADE nf_conntrack_netlink nft_counter xt_addrtype nft_compat br_netfilter bridge stp llc nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set overlay nf_tables nfnetlink crct10dif_pclmul crc32_pclmul ghash_clmulni_intel xfs serio_raw virtio_net virtio_blk net_failover failover fuse [last unloaded: sunrpc] [ 72.540389] CPU: 0 PID: 173 Comm: kworker/u16:5 Tainted: G OE 5.15.82-dan #1 [ 72.541511] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-3.module+el8.7.0+1084+97b81f61 04/01/2014 [ 72.542717] Workqueue: nfsd4_callbacks nfsd4_run_cb_work [nfsd] [ 72.543575] RIP: 0010:refcount_warn_saturate+0xcf/0x120 [ 72.544299] Code: 55 00 0f 0b 5d e9 01 50 98 00 80 3d 75 9e 39 08 00 0f 85 74 ff ff ff 48 c7 c7 e8 d1 60 8e c6 05 61 9e 39 08 01 e8 f6 51 55 00 <0f> 0b 5d e9 d9 4f 98 00 80 3d 4b 9e 39 08 00 0f 85 4c ff ff ff 48 [ 72.546666] RSP: 0018:ffffb3f841157cf0 EFLAGS: 00010286 [ 72.547393] RAX: 0000000000000026 RBX: ffff89ac6231d478 RCX: 0000000000000000 [ 72.548324] RDX: ffff89adb7c2c2c0 RSI: ffff89adb7c205c0 RDI: ffff89adb7c205c0 [ 72.549271] RBP: ffffb3f841157cf0 R08: 0000000000000000 R09: c0000000ffefffff [ 72.550209] R10: 0000000000000001 R11: ffffb3f841157ad0 R12: ffff89ac6231d180 [ 72.551142] R13: ffff89ac6231d478 R14: ffff89ac40c06180 R15: ffff89ac6231d4b0 [ 72.552089] FS: 0000000000000000(0000) GS:ffff89adb7c00000(0000) knlGS:0000000000000000 [ 72.553175] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 72.553934] CR2: 0000563a310506a8 CR3: 0000000109a66000 CR4: 0000000000350ef0 [ 72.554874] Call Trace: [ 72.555278] <TASK> [ 72.555614] svc_xprt_put+0xaf/0xe0 [sunrpc] [ 72.556276] nfsd4_process_cb_update.isra.11+0xb7/0x410 [nfsd] [ 72.557087] ? update_load_avg+0x82/0x610 [ 72.557652] ? cpuacct_charge+0x60/0x70 [ 72.558212] ? dequeue_entity+0xdb/0x3e0 [ 72.558765] ? queued_spin_unlock+0x9/0x20 [ 72.559358] nfsd4_run_cb_work+0xfc/0x270 [nfsd] [ 72.560031] process_one_work+0x1df/0x390 [ 72.560600] worker_thread+0x37/0x3b0 [ 72.561644] ? process_one_work+0x390/0x390 [ 72.562247] kthread+0x12f/0x150 [ 72.562710] ? set_kthread_struct+0x50/0x50 [ 72.563309] ret_from_fork+0x22/0x30 [ 72.563818] </TASK> [ 72.564189] ---[ end trace 031117b1c72ec616 ]--- [ 72.566019] list_add corruption. next->prev should be prev (ffff89ac4977e538), but was ffff89ac4763e018. (next=ffff89ac4763e018). [ 72.567647] ------------[ cut here ]------------
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Meta Information
Published
2025-09-18
Last Modified
2025-12-11
Generated
2026-05-07
AI Q&A
2025-09-18
EPSS Evaluated
2026-05-05
NVD
CVE-2022-50401
Affected Vendors & Products
Showing 9 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 4.4.229 (inc) to 4.5 (exc)
linux linux_kernel From 4.9.229 (inc) to 4.9.337 (exc)
linux linux_kernel From 4.14.186 (inc) to 4.14.303 (exc)
linux linux_kernel From 4.19.130 (inc) to 4.19.270 (exc)
linux linux_kernel From 5.4.49 (inc) to 5.4.229 (exc)
linux linux_kernel From 5.7.6 (inc) to 5.10.163 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.86 (exc)
linux linux_kernel From 5.16 (inc) to 6.0.16 (exc)
linux linux_kernel From 6.1 (inc) to 6.1.2 (exc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
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CWE ID Description
CWE-415 The product calls free() twice on the same memory address.
Attack-Flow Graph
AI Powered Q&A
How can this vulnerability impact me? :

The impact of this vulnerability includes possible kernel instability such as crashes or memory corruption due to use-after-free errors. This can affect the availability and reliability of systems running the vulnerable Linux kernel with NFSv4.1 server enabled, potentially leading to denial of service or other unpredictable behavior.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring kernel logs for specific error messages related to the nfsd module, such as 'refcount_t: underflow; use-after-free' or warnings from refcount_warn_saturate. You can check the kernel log using commands like 'dmesg | grep refcount' or 'journalctl -k | grep nfsd' to identify these error messages indicating the vulnerability is triggered.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include updating the Linux kernel to a version where this vulnerability is fixed, as the issue is resolved in the kernel by correcting the reference handling in nfsd under NFSv4.1. Until an update is applied, consider disabling or limiting NFSv4.1 services if possible to reduce exposure.


Can you explain this vulnerability to me?

This vulnerability is in the Linux kernel's NFS server (nfsd) implementation for NFSv4.1. It involves a double release (double svc_xprt_put) of a transport reference on an RPC creation failure. Specifically, when an error occurs, the code incorrectly gives a reference to the transport object that leads to it being released twice, causing a reference count underflow and use-after-free condition. This can lead to kernel warnings, potential crashes, or memory corruption.


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