Re: [PATCH] NFS: Fix potential buffer overflowin nfs_sysfs_link_rpc_client()

[Trond Myklebust <trondmy@hammerspace.com>]

On Tue, 2024-12-17 at 16:51 +0000, Trond Myklebust wrote:
> On Wed, 2024-12-18 at 00:13 +0800, Gax-c wrote:
> > From: Zichen Xie <zichenxie0106@gmail.com>
> > 
> > name is char[64] where the size of clnt->cl_program->name remains
> > unknown. Invoking strcat() directly will also lead to potential
> > buffer
> > overflow. Change them to strscpy() and strncat() to fix potential
> > issues.
> 
> What makes you think that clnt->cl_program->name is unknown?
> 
> All calls to nfs_sysfs_link_rpc_client() use well known RPC clients
> for
> which the cl_program is pointing to one of nlm_program, nfs_program
> or
> nfsacl_program. So we know very well the sizes of clnt->cl_program-
> > name.

Just to clarify: I'm not strongly against the patch itself. However it
would seem premature to consider this a bug, let alone a stable fix
candidate. 

Has anyone ever seen a buffer overflow here? If so, under which
circumstances?

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com