CVE-2026-89703: nfsd: set SC_STATUS_FREED in nfsd4_drop_revoked_stid for delegations

CVE-2026-89703: nfsd: set SC_STATUS_FREED in nfsd4_drop_revoked_stid for delegations

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

nfsd: set SC_STATUS_FREED in nfsd4_drop_revoked_stid for delegations

nfsd4_drop_revoked_stid() handles FREE_STATEID for admin-revoked
delegations but does not set SC_STATUS_FREED before releasing cl_lock.
revoke_delegation() uses this flag to detect whether FREE_STATEID has
already processed the delegation -- without it, the freed delegation is
added to cl_revoked via list_add(), producing a use-after-free when
cl_revoked is later traversed in __destroy_client().

The SC_STATUS_REVOKED path in nfsd4_free_stateid() (line 7983) already
sets SC_STATUS_FREED correctly. Apply the same pattern to the
SC_STATUS_ADMIN_REVOKED path in nfsd4_drop_revoked_stid().

The Linux kernel CVE team has assigned CVE-2026-89703 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.12 with commit 8dd91e8d31febf4d9cca3ae1bb4771d33ae7ee5a and fixed in 6.12.109 with commit d832a0587528853d45481d1faf75d4b5d062adaf
	Issue introduced in 6.12 with commit 8dd91e8d31febf4d9cca3ae1bb4771d33ae7ee5a and fixed in 6.18.50 with commit 1e4795766719ffd74b8cf0f2fde4a1350f8326bf
	Issue introduced in 6.12 with commit 8dd91e8d31febf4d9cca3ae1bb4771d33ae7ee5a and fixed in 7.2.4 with commit a6d89032e5c6620d5bb44582a72555ce07bf1c2e
	Issue introduced in 6.12 with commit 8dd91e8d31febf4d9cca3ae1bb4771d33ae7ee5a and fixed in 7.3-rc1 with commit 650d370cfbc66a96dd14d517bd704689b5bda4e5
	Issue introduced in 6.11.6 with commit 967faa26f313a62e7bebc55d5b8122eaee43b929

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-89703
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/nfsd/nfs4state.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/d832a0587528853d45481d1faf75d4b5d062adaf
	https://git.kernel.org/stable/c/1e4795766719ffd74b8cf0f2fde4a1350f8326bf
	https://git.kernel.org/stable/c/a6d89032e5c6620d5bb44582a72555ce07bf1c2e
	https://git.kernel.org/stable/c/650d370cfbc66a96dd14d517bd704689b5bda4e5