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    Subject[PATCH 131/222] nfsd4: fix oops on unusual readlike compound
    Date
    3.5.7.3 -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: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
    ---
    fs/nfsd/nfs4xdr.c | 11 ++++++++++-
    1 file changed, 10 insertions(+), 1 deletion(-)

    diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
    index 6322df3..1e83186 100644
    --- a/fs/nfsd/nfs4xdr.c
    +++ b/fs/nfsd/nfs4xdr.c
    @@ -2946,11 +2946,16 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
    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;
    }
    @@ -2996,6 +3001,8 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
    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++]);

    @@ -3045,6 +3052,8 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
    return nfserr;
    if (resp->xbuf->page_len)
    return nfserr_resource;
    + if (!resp->rqstp->rq_respages[resp->rqstp->rq_resused])
    + return nfserr_resource;

    RESERVE_SPACE(NFS4_VERIFIER_SIZE);
    savep = p;
    --
    1.7.9.5


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