nfs: fix UAF in direct writes

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2024-26958
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-05-01 06:15:12 UTC
Updated2026-05-12 12:16:27 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: nfs: fix UAF in direct writes In production we have been hitting the following warning consistently ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 17 PID: 1800359 at lib/refcount.c:28 refcount_warn_saturate+0x9c/0xe0 Workqueue: nfsiod nfs_direct_write_schedule_work [nfs] RIP: 0010:refcount_warn_saturate+0x9c/0xe0 PKRU: 55555554 Call Trace: <TASK> ? __warn+0x9f/0x130 ? refcount_warn_saturate+0x9c/0xe0 ? report_bug+0xcc/0x150 ? handle_bug+0x3d/0x70 ? exc_invalid_op+0x16/0x40 ? asm_exc_invalid_op+0x16/0x20 ? refcount_warn_saturate+0x9c/0xe0 nfs_direct_write_schedule_work+0x237/0x250 [nfs] process_one_work+0x12f/0x4a0 worker_thread+0x14e/0x3b0 ? ZSTD_getCParams_internal+0x220/0x220 kthread+0xdc/0x120 ? __btf_name_valid+0xa0/0xa0 ret_from_fork+0x1f/0x30 This is because we're completing the nfs_direct_request twice in a row. The source of this is when we have our commit requests to submit, we process them and send them off, and then in the completion path for the commit requests we have if (nfs_commit_end(cinfo.mds)) nfs_direct_write_complete(dreq); However since we're submitting asynchronous requests we sometimes have one that completes before we submit the next one, so we end up calling complete on the nfs_direct_request twice. The only other place we use nfs_generic_commit_list() is in __nfs_commit_inode, which wraps this call in a nfs_commit_begin(); nfs_commit_end(); Which is a common pattern for this style of completion handling, one that is also repeated in the direct code with get_dreq()/put_dreq() calls around where we process events as well as in the completion paths. Fix this by using the same pattern for the commit requests. Before with my 200 node rocksdb stress running this warning would pop every 10ish minutes. With my patch the stress test has been running for several hours without popping.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-416

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad 6cd3f13aaa62970b5169d990e936b2e96943bc6a git Not specified
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad 4595d90b5d2ea5fa4d318d13f59055aa4bf3e7f5 git Not specified
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad 80d24b308b7ee7037fc90d8ac99f6f78df0a256f git Not specified
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad 3abc2d160ed8213948b147295d77d44a22c88fa3 git Not specified
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad e25447c35f8745337ea8bc0c9697fcac14df8605 git Not specified
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad 1daf52b5ffb24870fbeda20b4967526d8f9e12ab git Not specified
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad cf54f66e1dd78990ec6b32177bca7e6ea2144a95 git Not specified
CNA Linux Linux affected af7cf057933f01dc7f33ddfb5e436ad598ed17ad 17f46b803d4f23c66cacce81db35fef3adb8f2af git Not specified
CNA Linux Linux affected 4.5 Not specified
CNA Linux Linux unaffected 4.5 semver Not specified
CNA Linux Linux unaffected 5.4.297 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.215 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.154 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.84 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.24 6.6.* semver Not specified
CNA Linux Linux unaffected 6.7.12 6.7.* semver Not specified
CNA Linux Linux unaffected 6.8.3 6.8.* semver Not specified
CNA Linux Linux unaffected 6.9 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 TM MFP - GNU/Linux Subsystem affected * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/17f46b803d4f23c66cacce81db35fef3adb8f2af af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2024/06/msg00017.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/80d24b308b7ee7037fc90d8ac99f6f78df0a256f af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-265688.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/6cd3f13aaa62970b5169d990e936b2e96943bc6a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3abc2d160ed8213948b147295d77d44a22c88fa3 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/4595d90b5d2ea5fa4d318d13f59055aa4bf3e7f5 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/e25447c35f8745337ea8bc0c9697fcac14df8605 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/cf54f66e1dd78990ec6b32177bca7e6ea2144a95 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/1daf52b5ffb24870fbeda20b4967526d8f9e12ab af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
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