Re: [PATCH net-next 2/2] xfrm: Fix unaligned access in xfrm_notify_sa() for DELSA
From: Sowmini Varadhan <hidden>
Date: 2015-10-21 12:36:56
Also in:
linux-crypto, lkml
Subsystem:
networking [general], networking [ipsec], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Steffen Klassert, Herbert Xu, Linus Torvalds
On (10/21/15 06:54), Sowmini Varadhan wrote:
But __alignof__(*p) is 8 on sparc, and without the patch I get all types of unaligned access. So what do you suggest as the fix?
Even though the alignment is, in fact, 8 (and that comes from struct xfrm_lifetime_cfg), if uspace is firmly attached to the 4 byte alignment, I think we can retain that behavior and still avoid unaligned access in the kernel with the following (admittedly ugly hack). Can you please take a look? I tested it with 'ip x m' and a transport mode tunnel on my sparc.
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 158ef4a..ca4e7f0 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c@@ -2620,7 +2620,7 @@ static inline size_t xfrm_sa_len(struct xfrm_state *x) static int xfrm_notify_sa(struct xfrm_state *x, const struct km_event *c) { struct net *net = xs_net(x); - struct xfrm_usersa_info *p; + struct xfrm_usersa_info *p, tmp; struct xfrm_usersa_id *id; struct nlmsghdr *nlh; struct sk_buff *skb;
@@ -2659,11 +2659,16 @@ static int xfrm_notify_sa(struct xfrm_state *x, const struct km_event *c) if (attr == NULL) goto out_free_skb; - p = PTR_ALIGN(nla_data(attr), __alignof__(*p)); + p = nla_data(attr); + err = copy_to_user_state_extra(x, &tmp, skb); + if (err) + goto out_free_skb; + memcpy((u8 *)p, &tmp, sizeof(tmp)); + } else { + err = copy_to_user_state_extra(x, p, skb); + if (err) + goto out_free_skb; } - err = copy_to_user_state_extra(x, p, skb); - if (err) - goto out_free_skb; nlmsg_end(skb, nlh);