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    Subject[ 40/85] svcrpc: fix BUG() in svc_tcp_clear_pages
    Date
    From: Greg KH <gregkh@linuxfoundation.org>

    3.4-stable review patch. If anyone has any objections, please let me know.

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

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

    commit be1e44441a560c43c136a562d49a1c9623c91197 upstream.

    Examination of svc_tcp_clear_pages shows that it assumes sk_tcplen is
    consistent with sk_pages[] (in particular, sk_pages[n] can't be NULL if
    sk_tcplen would lead us to expect n pages of data).

    svc_tcp_restore_pages zeroes out sk_pages[] while leaving sk_tcplen.
    This is OK, since both functions are serialized by XPT_BUSY. However,
    that means the inconsistency must be repaired before dropping XPT_BUSY.

    Therefore we should be ensuring that svc_tcp_save_pages repairs the
    problem before exiting svc_tcp_recv_record on error.

    Symptoms were a BUG() in svc_tcp_clear_pages.

    Signed-off-by: J. Bruce Fields <bfields@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/sunrpc/svcsock.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/net/sunrpc/svcsock.c
    +++ b/net/sunrpc/svcsock.c
    @@ -1137,9 +1137,9 @@ static int svc_tcp_recvfrom(struct svc_r
    if (len >= 0)
    svsk->sk_tcplen += len;
    if (len != want) {
    + svc_tcp_save_pages(svsk, rqstp);
    if (len < 0 && len != -EAGAIN)
    goto err_other;
    - svc_tcp_save_pages(svsk, rqstp);
    dprintk("svc: incomplete TCP record (%d of %d)\n",
    svsk->sk_tcplen, svsk->sk_reclen);
    goto err_noclose;



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