CVE-2026-89672

Summary

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

nfsd: gate nfs2 setacl by argp->mask

The NFSACL v2 SETACL path shares the decoder convention used by its v3 sibling: nfsaclsvc_decode_setaclargs() fills in argp->acl_access only when NFS_ACL is set in the request mask and argp->acl_default only when NFS_DFACL is set, leaving the other pointer NULL because the argument buffer is zeroed up to pc_argzero before decode.

nfsacld_proc_setacl() then hands both pointers to set_posix_acl() unconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation, so an omitted arm is indistinguishable from an explicit request to delete that ACL. A SETACL carrying only NFS_ACL silently strips the directory's default ACL; mask=0 strips both.

This is the same defect just fixed in nfsd3_proc_setacl(); apply the same remedy. Gate each set_posix_acl() call on its mask bit and initialize error to 0 so that a request with neither bit set leaves the on-disk ACLs untouched and returns success. The out_drop_lock path and the unconditional posix_acl_release() in nfsaclsvc_release_setacl() already tolerate the skipped arms.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/e41d173d9dc735cecb15ab7aa63ecab09338f81b
• https://git.kernel.org/stable/c/f951b22dbeec46f2e0fba81cb80d1b0c686b61eb
• https://git.kernel.org/stable/c/37eea38e7898538f0ec5f1eb8b18d8646e4be41c
• https://git.kernel.org/stable/c/a3a7e20ed66d3f04d37883c398da8a113b430769

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