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    Subject[04/68] sctp: Fix out-of-bounds reading in sctp_asoc_get_hmac()
    2.6.32-longterm review patch.  If anyone has any objections, please let us know.


    From: Dan Rosenberg <>

    commit 51e97a12bef19b7e43199fc153cf9bd5f2140362 upstream.

    The sctp_asoc_get_hmac() function iterates through a peer's hmac_ids
    array and attempts to ensure that only a supported hmac entry is
    returned. The current code fails to do this properly - if the last id
    in the array is out of range (greater than SCTP_AUTH_HMAC_ID_MAX), the
    id integer remains set after exiting the loop, and the address of an
    out-of-bounds entry will be returned and subsequently used in the parent
    function, causing potentially ugly memory corruption. This patch resets
    the id integer to 0 on encountering an invalid id so that NULL will be
    returned after finishing the loop if no valid ids are found.

    Signed-off-by: Dan Rosenberg <>
    Acked-by: Vlad Yasevich <>
    Signed-off-by: David S. Miller <>
    Signed-off-by: Greg Kroah-Hartman <>

    net/sctp/auth.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    --- a/net/sctp/auth.c
    +++ b/net/sctp/auth.c
    @@ -542,16 +542,20 @@ struct sctp_hmac *sctp_auth_asoc_get_hma
    id = ntohs(hmacs->hmac_ids[i]);

    /* Check the id is in the supported range */
    - if (id > SCTP_AUTH_HMAC_ID_MAX)
    + if (id > SCTP_AUTH_HMAC_ID_MAX) {
    + id = 0;
    + }

    /* See is we support the id. Supported IDs have name and
    * length fields set, so that we can allocated and use
    * them. We can safely just check for name, for without the
    * name, we can't allocate the TFM.
    - if (!sctp_hmac_list[id].hmac_name)
    + if (!sctp_hmac_list[id].hmac_name) {
    + id = 0;
    + }


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