From 5d9a7965b157f61040047e7006b987ac4a58278b Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Tue, 11 Dec 2018 14:10:08 -0600 Subject: ip6mr: Fix potential Spectre v1 vulnerability [ Upstream commit 69d2c86766da2ded2b70281f1bf242cb0d58a778 ] vr.mifi is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: net/ipv6/ip6mr.c:1845 ip6mr_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap) net/ipv6/ip6mr.c:1919 ip6mr_compat_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap) Fix this by sanitizing vr.mifi before using it to index mrt->vif_table' Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6mr.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/ipv6/ip6mr.c') diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index 4b93ad4fe6d8..ad597b4b22a0 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -72,6 +72,8 @@ struct mr6_table { #endif }; +#include + struct ip6mr_rule { struct fib_rule common; }; @@ -1873,6 +1875,7 @@ int ip6mr_ioctl(struct sock *sk, int cmd, void __user *arg) return -EFAULT; if (vr.mifi >= mrt->maxvif) return -EINVAL; + vr.mifi = array_index_nospec(vr.mifi, mrt->maxvif); read_lock(&mrt_lock); vif = &mrt->vif6_table[vr.mifi]; if (MIF_EXISTS(mrt, vr.mifi)) { @@ -1947,6 +1950,7 @@ int ip6mr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg) return -EFAULT; if (vr.mifi >= mrt->maxvif) return -EINVAL; + vr.mifi = array_index_nospec(vr.mifi, mrt->maxvif); read_lock(&mrt_lock); vif = &mrt->vif6_table[vr.mifi]; if (MIF_EXISTS(mrt, vr.mifi)) { -- cgit v1.2.3 From a5a32e427ba87d9c772958280e6edbc86e8929ad Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Sun, 3 Mar 2019 07:34:57 +0000 Subject: ip6mr: Do not call __IP6_INC_STATS() from preemptible context [ Upstream commit 87c11f1ddbbad38ad8bad47af133a8208985fbdf ] Similar to commit 44f49dd8b5a6 ("ipmr: fix possible race resulting from improper usage of IP_INC_STATS_BH() in preemptible context."), we cannot assume preemption is disabled when incrementing the counter and accessing a per-CPU variable. Preemption can be enabled when we add a route in process context that corresponds to packets stored in the unresolved queue, which are then forwarded using this route [1]. Fix this by using IP6_INC_STATS() which takes care of disabling preemption on architectures where it is needed. [1] [ 157.451447] BUG: using __this_cpu_add() in preemptible [00000000] code: smcrouted/2314 [ 157.460409] caller is ip6mr_forward2+0x73e/0x10e0 [ 157.460434] CPU: 3 PID: 2314 Comm: smcrouted Not tainted 5.0.0-rc7-custom-03635-g22f2712113f1 #1336 [ 157.460449] Hardware name: Mellanox Technologies Ltd. MSN2100-CB2FO/SA001017, BIOS 5.6.5 06/07/2016 [ 157.460461] Call Trace: [ 157.460486] dump_stack+0xf9/0x1be [ 157.460553] check_preemption_disabled+0x1d6/0x200 [ 157.460576] ip6mr_forward2+0x73e/0x10e0 [ 157.460705] ip6_mr_forward+0x9a0/0x1510 [ 157.460771] ip6mr_mfc_add+0x16b3/0x1e00 [ 157.461155] ip6_mroute_setsockopt+0x3cb/0x13c0 [ 157.461384] do_ipv6_setsockopt.isra.8+0x348/0x4060 [ 157.462013] ipv6_setsockopt+0x90/0x110 [ 157.462036] rawv6_setsockopt+0x4a/0x120 [ 157.462058] __sys_setsockopt+0x16b/0x340 [ 157.462198] __x64_sys_setsockopt+0xbf/0x160 [ 157.462220] do_syscall_64+0x14d/0x610 [ 157.462349] entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: 0912ea38de61 ("[IPV6] MROUTE: Add stats in multicast routing module method ip6_mr_forward().") Signed-off-by: Ido Schimmel Reported-by: Amit Cohen Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6mr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/ipv6/ip6mr.c') diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index ad597b4b22a0..41f67629ae59 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -1992,10 +1992,10 @@ int ip6mr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg) static inline int ip6mr_forward2_finish(struct net *net, struct sock *sk, struct sk_buff *skb) { - __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), - IPSTATS_MIB_OUTFORWDATAGRAMS); - __IP6_ADD_STATS(net, ip6_dst_idev(skb_dst(skb)), - IPSTATS_MIB_OUTOCTETS, skb->len); + IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), + IPSTATS_MIB_OUTFORWDATAGRAMS); + IP6_ADD_STATS(net, ip6_dst_idev(skb_dst(skb)), + IPSTATS_MIB_OUTOCTETS, skb->len); return dst_output(net, sk, skb); } -- cgit v1.2.3