| From foo@baz Fri Jan 4 19:53:50 CET 2019 |
| From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> |
| Date: Tue, 11 Dec 2018 14:10:08 -0600 |
| Subject: ip6mr: Fix potential Spectre v1 vulnerability |
| |
| From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> |
| |
| [ 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 <gustavo@embeddedor.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/ipv6/ip6mr.c | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| --- a/net/ipv6/ip6mr.c |
| +++ b/net/ipv6/ip6mr.c |
| @@ -72,6 +72,8 @@ struct mr6_table { |
| #endif |
| }; |
| |
| +#include <linux/nospec.h> |
| + |
| struct ip6mr_rule { |
| struct fib_rule common; |
| }; |
| @@ -1873,6 +1875,7 @@ int ip6mr_ioctl(struct sock *sk, int cmd |
| 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, |
| 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)) { |
