xfrm: fix stack access out of bounds with CONFIG_XFRM_SUB_POLICY

When CONFIG_XFRM_SUB_POLICY=y, xfrm_dst stores a copy of the flowi for
that dst. Unfortunately, the code that allocates and fills this copy
doesn't care about what type of flowi (flowi, flowi4, flowi6) gets
passed. In multiple code paths (from raw_sendmsg, from TCP when
replying to a FIN, in vxlan, geneve, and gre), the flowi that gets
passed to xfrm is actually an on-stack flowi4, so we end up reading
stuff from the stack past the end of the flowi4 struct.

Since xfrm_dst->origin isn't used anywhere following commit
ca116922afa8 ("xfrm: Eliminate "fl" and "pol" args to
xfrm_bundle_ok()."), just get rid of it.  xfrm_dst->partner isn't used
either, so get rid of that too.

Fixes: 9d6ec938019c ("ipv4: Use flowi4 in public route lookup interfaces.")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 6793a30c66b1f054516a27229c29037fcdfa2f6f..7e7e2b0d29157047fa0d3596b3f97cf501d754f9 100644 (file)
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -979,10 +979,6 @@ struct xfrm_dst {
        struct flow_cache_object flo;
        struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
        int num_pols, num_xfrms;
-#ifdef CONFIG_XFRM_SUB_POLICY
-       struct flowi *origin;
-       struct xfrm_selector *partner;
-#endif
        u32 xfrm_genid;
        u32 policy_genid;
        u32 route_mtu_cached;
@@ -998,12 +994,6 @@ static inline void xfrm_dst_destroy(struct xfrm_dst *xdst)
        dst_release(xdst->route);
        if (likely(xdst->u.dst.xfrm))
                xfrm_state_put(xdst->u.dst.xfrm);
-#ifdef CONFIG_XFRM_SUB_POLICY
-       kfree(xdst->origin);
-       xdst->origin = NULL;
-       kfree(xdst->partner);
-       xdst->partner = NULL;
-#endif
 }
 #endif
 

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index b00a1d5a7f52e54f2ac454da3eeb14447f84d8b2..ed4e52d95172e2d8dcca603cdf62cfb55517f3c9 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1797,43 +1797,6 @@ free_dst:
        goto out;
 }
 
-#ifdef CONFIG_XFRM_SUB_POLICY
-static int xfrm_dst_alloc_copy(void **target, const void *src, int size)
-{
-       if (!*target) {
-               *target = kmalloc(size, GFP_ATOMIC);
-               if (!*target)
-                       return -ENOMEM;
-       }
-
-       memcpy(*target, src, size);
-       return 0;
-}
-#endif
-
-static int xfrm_dst_update_parent(struct dst_entry *dst,
-                                 const struct xfrm_selector *sel)
-{
-#ifdef CONFIG_XFRM_SUB_POLICY
-       struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
-       return xfrm_dst_alloc_copy((void **)&(xdst->partner),
-                                  sel, sizeof(*sel));
-#else
-       return 0;
-#endif
-}
-
-static int xfrm_dst_update_origin(struct dst_entry *dst,
-                                 const struct flowi *fl)
-{
-#ifdef CONFIG_XFRM_SUB_POLICY
-       struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
-       return xfrm_dst_alloc_copy((void **)&(xdst->origin), fl, sizeof(*fl));
-#else
-       return 0;
-#endif
-}
-
 static int xfrm_expand_policies(const struct flowi *fl, u16 family,
                                struct xfrm_policy **pols,
                                int *num_pols, int *num_xfrms)
@@ -1905,16 +1868,6 @@ xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols,
 
        xdst = (struct xfrm_dst *)dst;
        xdst->num_xfrms = err;
-       if (num_pols > 1)
-               err = xfrm_dst_update_parent(dst, &pols[1]->selector);
-       else
-               err = xfrm_dst_update_origin(dst, fl);
-       if (unlikely(err)) {
-               dst_free(dst);
-               XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTBUNDLECHECKERROR);
-               return ERR_PTR(err);
-       }
-
        xdst->num_pols = num_pols;
        memcpy(xdst->pols, pols, sizeof(struct xfrm_policy *) * num_pols);
        xdst->policy_genid = atomic_read(&pols[0]->genid);