From 342ddb07be66138010864196e659053babdbbd03 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Wed, 22 Mar 2017 07:29:31 +0000 Subject: [PATCH 1/2] xfrm_user: validate XFRM_MSG_NEWAE XFRMA_REPLAY_ESN_VAL replay_window When a new xfrm state is created during an XFRM_MSG_NEWSA call we validate the user supplied replay_esn to ensure that the size is valid and to ensure that the replay_window size is within the allocated buffer. However later it is possible to update this replay_esn via a XFRM_MSG_NEWAE call. There we again validate the size of the supplied buffer matches the existing state and if so inject the contents. We do not at this point check that the replay_window is within the allocated memory. This leads to out-of-bounds reads and writes triggered by netlink packets. This leads to memory corruption and the potential for priviledge escalation. We already attempt to validate the incoming replay information in xfrm_new_ae() via xfrm_replay_verify_len(). This confirms that the user is not trying to change the size of the replay state buffer which includes the replay_esn. It however does not check the replay_window remains within that buffer. Add validation of the contained replay_window. CVE-2017-7184 Signed-off-by: Andy Whitcroft Acked-by: Steffen Klassert Signed-off-by: Linus Torvalds --- net/xfrm/xfrm_user.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 671a1d0333f0d2..98420bf914cedf 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -415,6 +415,9 @@ static inline int xfrm_replay_verify_len(struct xfrm_replay_state_esn *replay_es if (nla_len(rp) < ulen || xfrm_replay_state_esn_len(replay_esn) != ulen) return -EINVAL; + if (up->replay_window > up->bmp_len * sizeof(__u32) * 8) + return -EINVAL; + return 0; } From 91258cce259dd90adcae0e4ce1dcae809e94d008 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Thu, 23 Mar 2017 07:45:44 +0000 Subject: [PATCH 2/2] xfrm_user: validate XFRM_MSG_NEWAE incoming ESN size harder Kees Cook has pointed out that xfrm_replay_state_esn_len() is subject to wrapping issues. To ensure we are correctly ensuring that the two ESN structures are the same size compare both the overall size as reported by xfrm_replay_state_esn_len() and the internal length are the same. CVE-2017-7184 Signed-off-by: Andy Whitcroft Acked-by: Steffen Klassert Signed-off-by: Linus Torvalds --- net/xfrm/xfrm_user.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 98420bf914cedf..a7e27e1140dd3d 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -412,7 +412,11 @@ static inline int xfrm_replay_verify_len(struct xfrm_replay_state_esn *replay_es up = nla_data(rp); ulen = xfrm_replay_state_esn_len(up); - if (nla_len(rp) < ulen || xfrm_replay_state_esn_len(replay_esn) != ulen) + /* Check the overall length and the internal bitmap length to avoid + * potential overflow. */ + if (nla_len(rp) < ulen || + xfrm_replay_state_esn_len(replay_esn) != ulen || + replay_esn->bmp_len != up->bmp_len) return -EINVAL; if (up->replay_window > up->bmp_len * sizeof(__u32) * 8)