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    Subject[PATCH AUTOSEL for 4.14 142/161] nfsd: return RESOURCE not GARBAGE_ARGS on too many ops
    Date
    From: "J. Bruce Fields" <bfields@redhat.com>

    [ Upstream commit 0078117c6d9160031b866cfa1853514d4f6865d2 ]

    A client that sends more than a hundred ops in a single compound
    currently gets an rpc-level GARBAGE_ARGS error.

    It would be more helpful to return NFS4ERR_RESOURCE, since that gives
    the client a better idea how to recover (for example by splitting up the
    compound into smaller compounds).

    This is all a bit academic since we've never actually seen a reason for
    clients to send such long compounds, but we may as well fix it.

    While we're there, just use NFSD4_MAX_OPS_PER_COMPOUND == 16, the
    constant we already use in the 4.1 case, instead of hard-coding 100.
    Chances anyone actually uses even 16 ops per compound are small enough
    that I think there's a neglible risk or any regression.

    This fixes pynfs test COMP6.

    Reported-by: "Lu, Xinyu" <luxy.fnst@cn.fujitsu.com>
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    fs/nfsd/nfs4proc.c | 3 +++
    fs/nfsd/nfs4xdr.c | 9 +++++++--
    2 files changed, 10 insertions(+), 2 deletions(-)

    diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
    index 8ce60986fb75..8706b141e4a4 100644
    --- a/fs/nfsd/nfs4proc.c
    +++ b/fs/nfsd/nfs4proc.c
    @@ -1712,6 +1712,9 @@ nfsd4_proc_compound(struct svc_rqst *rqstp)
    status = nfserr_minor_vers_mismatch;
    if (nfsd_minorversion(args->minorversion, NFSD_TEST) <= 0)
    goto out;
    + status = nfserr_resource;
    + if (args->opcnt > NFSD_MAX_OPS_PER_COMPOUND)
    + goto out;

    status = nfs41_check_op_ordering(args);
    if (status) {
    diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
    index 2c61c6b8ae09..5dcd7cb45b2d 100644
    --- a/fs/nfsd/nfs4xdr.c
    +++ b/fs/nfsd/nfs4xdr.c
    @@ -1918,8 +1918,13 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)

    if (argp->taglen > NFSD4_MAX_TAGLEN)
    goto xdr_error;
    - if (argp->opcnt > 100)
    - goto xdr_error;
    + /*
    + * NFS4ERR_RESOURCE is a more helpful error than GARBAGE_ARGS
    + * here, so we return success at the xdr level so that
    + * nfsd4_proc can handle this is an NFS-level error.
    + */
    + if (argp->opcnt > NFSD_MAX_OPS_PER_COMPOUND)
    + return 0;

    if (argp->opcnt > ARRAY_SIZE(argp->iops)) {
    argp->ops = kzalloc(argp->opcnt * sizeof(*argp->ops), GFP_KERNEL);
    --
    2.15.1
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