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    Subject[PATCH 3.10 018/139] xfrm: policy: check policy direction value
    Date
    From: Vladis Dronov <vdronov@redhat.com>

    commit 7bab09631c2a303f87a7eb7e3d69e888673b9b7e upstream.

    The 'dir' parameter in xfrm_migrate() is a user-controlled byte which is used
    as an array index. This can lead to an out-of-bound access, kernel lockup and
    DoS. Add a check for the 'dir' value.

    This fixes CVE-2017-11600.

    References: https://bugzilla.redhat.com/show_bug.cgi?id=1474928
    Fixes: 80c9abaabf42 ("[XFRM]: Extension for dynamic update of endpoint address(es)")
    Cc: <stable@vger.kernel.org>
    Reported-by: "bo Zhang" <zhangbo5891001@gmail.com>
    Signed-off-by: Vladis Dronov <vdronov@redhat.com>
    Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
    Signed-off-by: Willy Tarreau <w@1wt.eu>
    ---
    net/xfrm/xfrm_policy.c | 6 ++++++
    1 file changed, 6 insertions(+)

    diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
    index ea970b8..10c556e 100644
    --- a/net/xfrm/xfrm_policy.c
    +++ b/net/xfrm/xfrm_policy.c
    @@ -3201,9 +3201,15 @@ int xfrm_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
    struct xfrm_state *x_new[XFRM_MAX_DEPTH];
    struct xfrm_migrate *mp;

    + /* Stage 0 - sanity checks */
    if ((err = xfrm_migrate_check(m, num_migrate)) < 0)
    goto out;

    + if (dir >= XFRM_POLICY_MAX) {
    + err = -EINVAL;
    + goto out;
    + }
    +
    /* Stage 1 - find policy */
    if ((pol = xfrm_migrate_policy_find(sel, dir, type)) == NULL) {
    err = -ENOENT;
    --
    2.8.0.rc2.1.gbe9624a
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