Re: [PATCH v3 3/3] nfsd: use NSEC_PER_SEC in nfsd4_decode_nfstime4()

On Tue, 2026-06-16 at 13:40 +0800, robbieko wrote:
> From: Robbie Ko <robbieko-UelDjCVBxVpWk0Htik3J/[email protected]>
> 
> nfsd4_decode_nfstime4() open-codes the nanoseconds upper bound as the
> literal (u32)1000000000. Use the named constant NSEC_PER_SEC instead,
> matching the NFSv3 setattr check and improving readability.
> 
> The original code cast the literal to u32 to force an unsigned
> comparison, which matters on 32-bit where tv_nsec is a 32-bit signed
> long: an out-of-range u32 wire nseconds (>= 0x80000000) assigned to it
> becomes negative and a signed compare against NSEC_PER_SEC (a signed
> long) would wrongly pass. Keep that protection by casting tv_nsec to
> unsigned long, the same width as tv_nsec, matching timespec64_valid().
> No functional change.
> 
> Signed-off-by: Robbie Ko <robbieko-UelDjCVBxVpWk0Htik3J/[email protected]>
> ---
>  fs/nfsd/nfs4xdr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 2a0946c630e1..db17bd3e45d6 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -244,7 +244,7 @@ nfsd4_decode_nfstime4(struct nfsd4_compoundargs *argp, struct timespec64 *tv)
>  		return nfserr_bad_xdr;
>  	p = xdr_decode_hyper(p, &tv->tv_sec);
>  	tv->tv_nsec = be32_to_cpup(p++);
> -	if (tv->tv_nsec >= (u32)1000000000)
> +	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
>  		return nfserr_inval;
>  	return nfs_ok;
>  }

Reviewed-by: Jeff Layton <[email protected]>