4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vladis Dronov <vdronov@xxxxxxxxxx> 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)") Reported-by: "bo Zhang" <zhangbo5891001@xxxxxxxxx> Signed-off-by: Vladis Dronov <vdronov@xxxxxxxxxx> Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/xfrm/xfrm_policy.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -3275,9 +3275,15 @@ int xfrm_migrate(const struct xfrm_selec 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, net)) == NULL) { err = -ENOENT;