From 2f97a86170c0d32681cd70c2e76e7b1c2b0396af Mon Sep 17 00:00:00 2001 From: Sabrina Dubroca Date: Wed, 3 May 2017 16:43:19 +0200 Subject: [PATCH] xfrm: fix stack access out of bounds with CONFIG_XFRM_SUB_POLICY commit 9b3eb54106cf6acd03f07cf0ab01c13676a226c2 upstream. 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 Signed-off-by: Steffen Klassert [bwh: Backported to 3.2: deleted code is slightly different] Signed-off-by: Ben Hutchings --- include/net/xfrm.h | 10 ---------- net/xfrm/xfrm_policy.c | 45 ------------------------------------------ 2 files changed, 55 deletions(-) diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 94ce082b29dc..7b6e0fa9f7ad 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -944,10 +944,6 @@ 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; @@ -963,12 +959,6 @@ 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 10c556e373b0..9c9c2f0c4091 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1629,41 +1629,6 @@ free_dst: goto out; } -static int inline -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; -} - -static int inline -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 inline -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) @@ -1735,16 +1700,6 @@ 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);