CVE-2026-53396

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

nfsd: fix posix_acl leak and ignored error in nfsd4_create_file

nfsd4_create_file() has two bugs in its ACL handling:

The return value of nfsd4_acl_to_attr() is silently discarded. When

the NFSv4-to-POSIX ACL conversion fails (e.g., -EINVAL for

unsupported ACE types), the file is created without any ACL and the

client receives NFS4_OK. This violates RFC 7530/8881 which require

the server to reject unsupported attributes on CREATE.

When start_creating() fails after ACL attributes have been populated

in attrs (either via nfsd4_acl_to_attr or via ownership transfer from

open->op_dpacl/op_pacl), the function jumps to out_write which skips

nfsd_attrs_free(). The posix_acl allocations are leaked. A client

can trigger this repeatedly with OPEN(CREATE), ACL attributes, and an

invalid filename (e.g., longer than NAME_MAX).

Fix both by capturing the nfsd4_acl_to_attr() return value and by

changing the early error paths to jump to out instead of out_write.

Initialize child to ERR_PTR(-EINVAL) so that end_creating() is safe

to call even if start_creating() was never reached.