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    Subject[ 139/173] nfsd4: fix oops on unusual readlike compound
    3.2-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: "J. Bruce Fields" <bfields@redhat.com>

    commit d5f50b0c290431c65377c4afa1c764e2c3fe5305 upstream.

    If the argument and reply together exceed the maximum payload size, then
    a reply with a read-like operation can overlow the rq_pages array.

    Signed-off-by: J. Bruce Fields <bfields@redhat.com>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    fs/nfsd/nfs4xdr.c | 11 ++++++++++-
    1 file changed, 10 insertions(+), 1 deletion(-)

    --- a/fs/nfsd/nfs4xdr.c
    +++ b/fs/nfsd/nfs4xdr.c
    @@ -2909,11 +2909,16 @@ nfsd4_encode_read(struct nfsd4_compoundr
    len = maxcount;
    v = 0;
    while (len > 0) {
    - pn = resp->rqstp->rq_resused++;
    + pn = resp->rqstp->rq_resused;
    + if (!resp->rqstp->rq_respages[pn]) { /* ran out of pages */
    + maxcount -= len;
    + break;
    + }
    resp->rqstp->rq_vec[v].iov_base =
    page_address(resp->rqstp->rq_respages[pn]);
    resp->rqstp->rq_vec[v].iov_len =
    len < PAGE_SIZE ? len : PAGE_SIZE;
    + resp->rqstp->rq_resused++;
    v++;
    len -= PAGE_SIZE;
    }
    @@ -2959,6 +2964,8 @@ nfsd4_encode_readlink(struct nfsd4_compo
    return nfserr;
    if (resp->xbuf->page_len)
    return nfserr_resource;
    + if (!resp->rqstp->rq_respages[resp->rqstp->rq_resused])
    + return nfserr_resource;

    page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused++]);

    @@ -3008,6 +3015,8 @@ nfsd4_encode_readdir(struct nfsd4_compou
    return nfserr;
    if (resp->xbuf->page_len)
    return nfserr_resource;
    + if (!resp->rqstp->rq_respages[resp->rqstp->rq_resused])
    + return nfserr_resource;

    RESERVE_SPACE(8); /* verifier */
    savep = p;



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