2018-05-07 13:01:09

by Scott Mayhew

Subject: [PATCH] nfsd: restrict rd_maxcount to svc_max_payload in nfsd_encode_readdir

nfsd4_readdir_rsize restricts rd_maxcount to svc_max_payload when
estimating the size of the readdir reply, but nfsd_encode_readdir
restricts it to INT_MAX when encoding the reply. This can result in log
messages like "kernel: RPC request reserved 32896 but used 1049444".

Restrict rd_dircount similarly (no reason it should be larger than
svc_max_payload).

Signen-off-by: Scott Mayhew <[email protected]>
---
fs/nfsd/nfs4xdr.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 1d048dd..cfe535c 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3651,7 +3651,8 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
nfserr = nfserr_resource;
goto err_no_verf;
}
- maxcount = min_t(u32, readdir->rd_maxcount, INT_MAX);
+ maxcount = svc_max_payload(resp->rqstp);
+ maxcount = min_t(u32, readdir->rd_maxcount, maxcount);
/*
* Note the rfc defines rd_maxcount as the size of the
* READDIR4resok structure, which includes the verifier above
@@ -3665,7 +3666,7 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4

/* RFC 3530 14.2.24 allows us to ignore dircount when it's 0: */
if (!readdir->rd_dircount)
- readdir->rd_dircount = INT_MAX;
+ readdir->rd_dircount = svc_max_payload(resp->rqstp);

readdir->xdr = xdr;
readdir->rd_maxcount = maxcount;
--
2.9.5

2018-05-07 16:55:34

by J. Bruce Fields

Subject: Re: [PATCH] nfsd: restrict rd_maxcount to svc_max_payload in nfsd_encode_readdir

Thanks, applying for 4.17 and stable.--b.

On Mon, May 07, 2018 at 09:01:08AM -0400, Scott Mayhew wrote:
> nfsd4_readdir_rsize restricts rd_maxcount to svc_max_payload when
> estimating the size of the readdir reply, but nfsd_encode_readdir
> restricts it to INT_MAX when encoding the reply. This can result in log
> messages like "kernel: RPC request reserved 32896 but used 1049444".
>
> Restrict rd_dircount similarly (no reason it should be larger than
> svc_max_payload).
>
> Signen-off-by: Scott Mayhew <[email protected]>
> ---
> fs/nfsd/nfs4xdr.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 1d048dd..cfe535c 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3651,7 +3651,8 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
> nfserr = nfserr_resource;
> goto err_no_verf;
> }
> - maxcount = min_t(u32, readdir->rd_maxcount, INT_MAX);
> + maxcount = svc_max_payload(resp->rqstp);
> + maxcount = min_t(u32, readdir->rd_maxcount, maxcount);
> /*
> * Note the rfc defines rd_maxcount as the size of the
> * READDIR4resok structure, which includes the verifier above
> @@ -3665,7 +3666,7 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
>
> /* RFC 3530 14.2.24 allows us to ignore dircount when it's 0: */
> if (!readdir->rd_dircount)
> - readdir->rd_dircount = INT_MAX;
> + readdir->rd_dircount = svc_max_payload(resp->rqstp);
>
> readdir->xdr = xdr;
> readdir->rd_maxcount = maxcount;
> --
> 2.9.5