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    Subject[PATCH 4.19 33/50] sctp: account stream padding length for reconf chunk
    Date
    From: Eiichi Tsukata <eiichi.tsukata@nutanix.com>

    commit a2d859e3fc97e79d907761550dbc03ff1b36479c upstream.

    sctp_make_strreset_req() makes repeated calls to sctp_addto_chunk()
    which will automatically account for padding on each call. inreq and
    outreq are already 4 bytes aligned, but the payload is not and doing
    SCTP_PAD4(a + b) (which _sctp_make_chunk() did implicitly here) is
    different from SCTP_PAD4(a) + SCTP_PAD4(b) and not enough. It led to
    possible attempt to use more buffer than it was allocated and triggered
    a BUG_ON.

    Cc: Vlad Yasevich <vyasevich@gmail.com>
    Cc: Neil Horman <nhorman@tuxdriver.com>
    Cc: Greg KH <gregkh@linuxfoundation.org>
    Fixes: cc16f00f6529 ("sctp: add support for generating stream reconf ssn reset request chunk")
    Reported-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
    Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
    Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
    Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
    Reviewed-by: Xin Long <lucien.xin@gmail.com>
    Link: https://lore.kernel.org/r/b97c1f8b0c7ff79ac4ed206fc2c49d3612e0850c.1634156849.git.mleitner@redhat.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/sctp/sm_make_chunk.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/net/sctp/sm_make_chunk.c
    +++ b/net/sctp/sm_make_chunk.c
    @@ -3673,7 +3673,7 @@ struct sctp_chunk *sctp_make_strreset_re
    outlen = (sizeof(outreq) + stream_len) * out;
    inlen = (sizeof(inreq) + stream_len) * in;

    - retval = sctp_make_reconf(asoc, outlen + inlen);
    + retval = sctp_make_reconf(asoc, SCTP_PAD4(outlen) + SCTP_PAD4(inlen));
    if (!retval)
    return NULL;


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