From: Claudio Jeker <cjeker@diehard.n-r-g.com>
Subject: Re: IP6_EXTHDR_GET pass mbuf pointer
To: Alexander Bluhm <bluhm@openbsd.org>
Cc: tech@openbsd.org
Date: Thu, 22 May 2025 16:25:57 +0200

On Thu, May 22, 2025 at 11:08:06PM +0900, Alexander Bluhm wrote:
> Hi,
> 
> I would like to pass an mbuf pointer instead of an mbuf to
> IP6_EXTHDR_GET().  m_pulldown() may free the mbuf and the macro
> sets m to NULL.  This is not obvious, it is much cleaner when you
> pass a pointer if the value can be modified.
> 
> The main reason for this change is that I am slowly converting the
> protocol input functions to deal with mbuf pointer instead of mbuf.
> m_pullup() and m_pulldown() may modify or free the mbuf, and then
> dangling pointers are lying around in the callers.  We had problmes
> with that before.
> 
> I would prefer to adjust all pointers, which is possible when using
> *mp instead of m and setting mp to NULL after free.  Then either a
> NULL dereference happens or a double free is ignored.  Both are
> much easier to deal with than a use after free.
> 
> I have done a similar change with m_freemp(mp) some years ago,
> IP6_EXTHDR_GET() is the next interface on my list.
> 
> ok?

Would it make sense to actually kill this macro and make it a proper
function? This thing is a monster and it probably makes things slower if
anything.
 
> bluhm
> 
> Index: netinet/ip6.h
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/ip6.h,v
> diff -u -p -r1.21 ip6.h
> --- netinet/ip6.h	1 Jan 2025 13:44:22 -0000	1.21
> +++ netinet/ip6.h	22 May 2025 06:50:06 -0000
> @@ -272,21 +272,21 @@ struct ip6_frag {
>   * The pointer to the region will be returned to pointer variable "val",
>   * with type "typ".
>   */
> -#define IP6_EXTHDR_GET(val, typ, m, off, len)				\
> +#define IP6_EXTHDR_GET(val, typ, mp, off, len)				\
>  do {									\
>  	struct mbuf *t;							\
>  	int tmp;							\
> -	if ((m)->m_len >= (off) + (len))				\
> -		(val) = (typ)(mtod((m), caddr_t) + (off));		\
> +	if ((*(mp))->m_len >= (off) + (len))				\
> +		(val) = (typ)(mtod((*(mp)), caddr_t) + (off));		\
>  	else {								\
> -		t = m_pulldown((m), (off), (len), &tmp);		\
> +		t = m_pulldown((*(mp)), (off), (len), &tmp);		\
>  		if (t) {						\
>  			if (t->m_len < tmp + (len))			\
>  				panic("m_pulldown malfunction");	\
>  			(val) = (typ)(mtod(t, caddr_t) + tmp);		\
>  		} else {						\
>  			(val) = (typ)NULL;				\
> -			(m) = NULL;					\
> +			(*(mp)) = NULL;					\
>  		}							\
>  	}								\
>  } while (/* CONSTCOND */ 0)
> Index: netinet/tcp_input.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/tcp_input.c,v
> diff -u -p -r1.447 tcp_input.c
> --- netinet/tcp_input.c	19 May 2025 02:27:57 -0000	1.447
> +++ netinet/tcp_input.c	22 May 2025 06:51:19 -0000
> @@ -448,7 +448,7 @@ tcp_input_solocked(struct mbuf **mp, int
>  	 * Get IP and TCP header together in first mbuf.
>  	 * Note: IP leaves IP header in first mbuf.
>  	 */
> -	IP6_EXTHDR_GET(th, struct tcphdr *, m, iphlen, sizeof(*th));
> +	IP6_EXTHDR_GET(th, struct tcphdr *, mp, iphlen, sizeof(*th));
>  	if (!th) {
>  		tcpstat_inc(tcps_rcvshort);
>  		return IPPROTO_DONE;
> @@ -532,7 +532,7 @@ tcp_input_solocked(struct mbuf **mp, int
>  	}
>  	tlen -= off;
>  	if (off > sizeof(struct tcphdr)) {
> -		IP6_EXTHDR_GET(th, struct tcphdr *, m, iphlen, off);
> +		IP6_EXTHDR_GET(th, struct tcphdr *, mp, iphlen, off);
>  		if (!th) {
>  			tcpstat_inc(tcps_rcvshort);
>  			return IPPROTO_DONE;
> Index: netinet/udp_usrreq.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/udp_usrreq.c,v
> diff -u -p -r1.337 udp_usrreq.c
> --- netinet/udp_usrreq.c	12 May 2025 17:21:21 -0000	1.337
> +++ netinet/udp_usrreq.c	22 May 2025 06:52:01 -0000
> @@ -213,7 +213,7 @@ udp_input(struct mbuf **mp, int *offp, i
>  
>  	udpstat_inc(udps_ipackets);
>  
> -	IP6_EXTHDR_GET(uh, struct udphdr *, m, iphlen, sizeof(struct udphdr));
> +	IP6_EXTHDR_GET(uh, struct udphdr *, mp, iphlen, sizeof(struct udphdr));
>  	if (!uh) {
>  		udpstat_inc(udps_hdrops);
>  		return IPPROTO_DONE;
> Index: netinet6/dest6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/dest6.c,v
> diff -u -p -r1.21 dest6.c
> --- netinet6/dest6.c	2 Mar 2025 21:28:32 -0000	1.21
> +++ netinet6/dest6.c	22 May 2025 06:53:25 -0000
> @@ -57,12 +57,12 @@ dest6_input(struct mbuf **mp, int *offp,
>  	u_int8_t *opt;
>  
>  	/* validation of the length of the header */
> -	IP6_EXTHDR_GET(dstopts, struct ip6_dest *, *mp, off, sizeof(*dstopts));
> +	IP6_EXTHDR_GET(dstopts, struct ip6_dest *, mp, off, sizeof(*dstopts));
>  	if (dstopts == NULL)
>  		return IPPROTO_DONE;
>  	dstoptlen = (dstopts->ip6d_len + 1) << 3;
>  
> -	IP6_EXTHDR_GET(dstopts, struct ip6_dest *, *mp, off, dstoptlen);
> +	IP6_EXTHDR_GET(dstopts, struct ip6_dest *, mp, off, dstoptlen);
>  	if (dstopts == NULL)
>  		return IPPROTO_DONE;
>  	off += dstoptlen;
> Index: netinet6/frag6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/frag6.c,v
> diff -u -p -r1.90 frag6.c
> --- netinet6/frag6.c	2 Mar 2025 21:28:32 -0000	1.90
> +++ netinet6/frag6.c	22 May 2025 07:06:00 -0000
> @@ -114,7 +114,7 @@ int
>  frag6_input(struct mbuf **mp, int *offp, int proto, int af,
>      struct netstack *ns)
>  {
> -	struct mbuf *m = *mp, *t;
> +	struct mbuf *t;
>  	struct ip6_hdr *ip6;
>  	struct ip6_frag *ip6f;
>  	struct ip6q *q6;
> @@ -124,14 +124,14 @@ frag6_input(struct mbuf **mp, int *offp,
>  	int fragoff, frgpartlen;	/* must be larger than u_int16_t */
>  	u_int8_t ecn, ecn0;
>  
> -	ip6 = mtod(m, struct ip6_hdr *);
> -	IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
> +	ip6 = mtod(*mp, struct ip6_hdr *);
> +	IP6_EXTHDR_GET(ip6f, struct ip6_frag *, mp, offset, sizeof(*ip6f));
>  	if (ip6f == NULL)
>  		return IPPROTO_DONE;
>  
>  	/* jumbo payload can't contain a fragment header */
>  	if (ip6->ip6_plen == 0) {
> -		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
> +		icmp6_error(*mp, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
>  		    offset);
>  		return IPPROTO_DONE;
>  	}
> @@ -144,7 +144,7 @@ frag6_input(struct mbuf **mp, int *offp,
>  	 */
>  	if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
>  	    (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
> -		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
> +		icmp6_error(*mp, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
>  		    offsetof(struct ip6_hdr, ip6_plen));
>  		return IPPROTO_DONE;
>  	}
> @@ -169,7 +169,7 @@ frag6_input(struct mbuf **mp, int *offp,
>  
>  	/* Ignore empty non atomic fragment, do not classify as overlapping. */
>  	if (sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) <= offset) {
> -		m_freem(m);
> +		m_freemp(mp);
>  		return IPPROTO_DONE;
>  	}
>  
> @@ -249,14 +249,15 @@ frag6_input(struct mbuf **mp, int *offp,
>  		/* The 1st fragment has already arrived. */
>  		if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
>  			mtx_leave(&frag6_mutex);
> -			icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
> +			icmp6_error(*mp, ICMP6_PARAM_PROB,
> +			    ICMP6_PARAMPROB_HEADER,
>  			    offset - sizeof(struct ip6_frag) +
>  			    offsetof(struct ip6_frag, ip6f_offlg));
>  			return (IPPROTO_DONE);
>  		}
>  	} else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
>  		mtx_leave(&frag6_mutex);
> -		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
> +		icmp6_error(*mp, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
>  			    offset - sizeof(struct ip6_frag) +
>  				offsetof(struct ip6_frag, ip6f_offlg));
>  		return (IPPROTO_DONE);
> @@ -304,7 +305,7 @@ frag6_input(struct mbuf **mp, int *offp,
>  	ip6af->ip6af_off = fragoff;
>  	ip6af->ip6af_frglen = frgpartlen;
>  	ip6af->ip6af_offset = offset;
> -	ip6af->ip6af_m = m;
> +	ip6af->ip6af_m = *mp;
>  
>  	if (first_frag) {
>  		paf6 = NULL;
> @@ -392,7 +393,7 @@ frag6_input(struct mbuf **mp, int *offp,
>  	 */
>  	ip6af = LIST_FIRST(&q6->ip6q_asfrag);
>  	LIST_REMOVE(ip6af, ip6af_list);
> -	t = m = ip6af->ip6af_m;
> +	t = *mp = ip6af->ip6af_m;
>  	while ((af6 = LIST_FIRST(&q6->ip6q_asfrag)) != NULL) {
>  		LIST_REMOVE(af6, ip6af_list);
>  		while (t->m_next)
> @@ -415,7 +416,7 @@ frag6_input(struct mbuf **mp, int *offp,
>  		pool_put(&ip6q_pool, q6);
>  		goto dropfrag;
>  	}
> -	ip6 = mtod(m, struct ip6_hdr *);
> +	ip6 = mtod(*mp, struct ip6_hdr *);
>  	ip6->ip6_plen = htons(next);
>  	ip6->ip6_src = q6->ip6q_src;
>  	ip6->ip6_dst = q6->ip6q_dst;
> @@ -424,7 +425,7 @@ frag6_input(struct mbuf **mp, int *offp,
>  	nxt = q6->ip6q_nxt;
>  
>  	/* Delete frag6 header */
> -	if (frag6_deletefraghdr(m, offset) != 0) {
> +	if (frag6_deletefraghdr(*mp, offset) != 0) {
>  		TAILQ_REMOVE(&frag6_queue, q6, ip6q_queue);
>  		frag6_nfrags -= q6->ip6q_nfrag;
>  		frag6_nfragpackets--;
> @@ -441,16 +442,16 @@ frag6_input(struct mbuf **mp, int *offp,
>  
>  	pool_put(&ip6q_pool, q6);
>  
> -	m_calchdrlen(m);
> +	m_calchdrlen(*mp);
>  
>  	/*
>  	 * Restore NXT to the original.
>  	 */
>  	{
> -		int prvnxt = ip6_get_prevhdr(m, offset);
> +		int prvnxt = ip6_get_prevhdr(*mp, offset);
>  		uint8_t *prvnxtp;
>  
> -		IP6_EXTHDR_GET(prvnxtp, uint8_t *, m, prvnxt,
> +		IP6_EXTHDR_GET(prvnxtp, uint8_t *, mp, prvnxt,
>  		    sizeof(*prvnxtp));
>  		if (prvnxtp == NULL)
>  			goto dropfrag;
> @@ -462,10 +463,7 @@ frag6_input(struct mbuf **mp, int *offp,
>  	/*
>  	 * Tell launch routine the next header
>  	 */
> -
> -	*mp = m;
>  	*offp = offset;
> -
>  	return nxt;
>  
>   flushfrags:
> @@ -484,12 +482,12 @@ frag6_input(struct mbuf **mp, int *offp,
>  	}
>  	ip6stat_add(ip6s_fragdropped, q6->ip6q_nfrag + 1);
>  	pool_put(&ip6q_pool, q6);
> -	m_freem(m);
> +	m_freemp(mp);
>  	return IPPROTO_DONE;
>  
>   dropfrag:
>  	ip6stat_inc(ip6s_fragdropped);
> -	m_freem(m);
> +	m_freemp(mp);
>  	return IPPROTO_DONE;
>  }
>  
> Index: netinet6/icmp6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/icmp6.c,v
> diff -u -p -r1.264 icmp6.c
> --- netinet6/icmp6.c	19 May 2025 07:34:21 -0000	1.264
> +++ netinet6/icmp6.c	22 May 2025 07:23:54 -0000
> @@ -281,7 +281,7 @@ icmp6_do_error(struct mbuf *m, int type,
>  	if (off >= 0 && nxt == IPPROTO_ICMPV6) {
>  		struct icmp6_hdr *icp;
>  
> -		IP6_EXTHDR_GET(icp, struct icmp6_hdr *, m, off,
> +		IP6_EXTHDR_GET(icp, struct icmp6_hdr *, &m, off,
>  			sizeof(*icp));
>  		if (icp == NULL) {
>  			icmp6stat_inc(icp6s_tooshort);
> @@ -407,7 +407,7 @@ icmp6_input(struct mbuf **mp, int *offp,
>  	/*
>  	 * calculate the checksum
>  	 */
> -	IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off, sizeof(*icmp6));
> +	IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, mp, off, sizeof(*icmp6));
>  	if (icmp6 == NULL) {
>  		icmp6stat_inc(icp6s_tooshort);
>  		return IPPROTO_DONE;
> @@ -588,7 +588,7 @@ icmp6_input(struct mbuf **mp, int *offp,
>  			n->m_next = n0;
>  		} else {
>  	 deliverecho:
> -			IP6_EXTHDR_GET(nicmp6, struct icmp6_hdr *, n, off,
> +			IP6_EXTHDR_GET(nicmp6, struct icmp6_hdr *, &n, off,
>  			    sizeof(*nicmp6));
>  			noff = off;
>  		}
> @@ -762,7 +762,7 @@ icmp6_notify_error(struct mbuf *m, int o
>  		icmp6stat_inc(icp6s_tooshort);
>  		goto freeit;
>  	}
> -	IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off,
> +	IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, &m, off,
>  		       sizeof(*icmp6) + sizeof(struct ip6_hdr));
>  	if (icmp6 == NULL) {
>  		icmp6stat_inc(icp6s_tooshort);
> @@ -791,7 +791,7 @@ icmp6_notify_error(struct mbuf *m, int o
>  			case IPPROTO_HOPOPTS:
>  			case IPPROTO_DSTOPTS:
>  			case IPPROTO_AH:
> -				IP6_EXTHDR_GET(eh, struct ip6_ext *, m,
> +				IP6_EXTHDR_GET(eh, struct ip6_ext *, &m,
>  					       eoff, sizeof(*eh));
>  				if (eh == NULL) {
>  					icmp6stat_inc(icp6s_tooshort);
> @@ -813,7 +813,7 @@ icmp6_notify_error(struct mbuf *m, int o
>  				 * information that depends on the final
>  				 * destination (e.g. path MTU).
>  				 */
> -				IP6_EXTHDR_GET(rth, struct ip6_rthdr *, m,
> +				IP6_EXTHDR_GET(rth, struct ip6_rthdr *, &m,
>  					       eoff, sizeof(*rth));
>  				if (rth == NULL) {
>  					icmp6stat_inc(icp6s_tooshort);
> @@ -833,7 +833,7 @@ icmp6_notify_error(struct mbuf *m, int o
>  					int hops;
>  
>  					IP6_EXTHDR_GET(rth0,
> -						       struct ip6_rthdr0 *, m,
> +						       struct ip6_rthdr0 *, &m,
>  						       eoff, rthlen);
>  					if (rth0 == NULL) {
>  						icmp6stat_inc(icp6s_tooshort);
> @@ -848,7 +848,7 @@ icmp6_notify_error(struct mbuf *m, int o
>  				nxt = rth->ip6r_nxt;
>  				break;
>  			case IPPROTO_FRAGMENT:
> -				IP6_EXTHDR_GET(fh, struct ip6_frag *, m,
> +				IP6_EXTHDR_GET(fh, struct ip6_frag *, &m,
>  					       eoff, sizeof(*fh));
>  				if (fh == NULL) {
>  					icmp6stat_inc(icp6s_tooshort);
> @@ -879,7 +879,7 @@ icmp6_notify_error(struct mbuf *m, int o
>  			}
>  		}
>  	  notify:
> -		IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off,
> +		IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, &m, off,
>  			       sizeof(*icmp6) + sizeof(struct ip6_hdr));
>  		if (icmp6 == NULL) {
>  			icmp6stat_inc(icp6s_tooshort);
> @@ -1204,7 +1204,7 @@ icmp6_redirect_input(struct mbuf *m, int
>  	if (!(ifp->if_xflags & IFXF_AUTOCONF6))
>  		goto freeit;
>  
> -	IP6_EXTHDR_GET(nd_rd, struct nd_redirect *, m, off, icmp6len);
> +	IP6_EXTHDR_GET(nd_rd, struct nd_redirect *, &m, off, icmp6len);
>  	if (nd_rd == NULL) {
>  		icmp6stat_inc(icp6s_tooshort);
>  		if_put(ifp);
> Index: netinet6/ip6_input.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/ip6_input.c,v
> diff -u -p -r1.270 ip6_input.c
> --- netinet6/ip6_input.c	19 May 2025 06:38:33 -0000	1.270
> +++ netinet6/ip6_input.c	22 May 2025 07:11:35 -0000
> @@ -685,7 +685,7 @@ ip6_hbhchcheck(struct mbuf **mp, int *of
>  				    (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
>  			goto bad;
>  		}
> -		IP6_EXTHDR_GET(hbh, struct ip6_hbh *, *mp,
> +		IP6_EXTHDR_GET(hbh, struct ip6_hbh *, mp,
>  		    sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
>  		if (hbh == NULL) {
>  			ip6stat_inc(ip6s_tooshort);
> @@ -814,14 +814,14 @@ ip6_hopopts_input(struct mbuf **mp, int 
>  	struct ip6_hbh *hbh;
>  
>  	/* validation of the length of the header */
> -	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, *mp,
> +	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, mp,
>  		sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
>  	if (hbh == NULL) {
>  		ip6stat_inc(ip6s_tooshort);
>  		return -1;
>  	}
>  	hbhlen = (hbh->ip6h_len + 1) << 3;
> -	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, *mp, sizeof(struct ip6_hdr),
> +	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, mp, sizeof(struct ip6_hdr),
>  		hbhlen);
>  	if (hbh == NULL) {
>  		ip6stat_inc(ip6s_tooshort);
> Index: netinet6/mld6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/mld6.c,v
> diff -u -p -r1.65 mld6.c
> --- netinet6/mld6.c	2 Mar 2025 21:28:32 -0000	1.65
> +++ netinet6/mld6.c	22 May 2025 07:16:49 -0000
> @@ -179,7 +179,7 @@ mld6_input(struct mbuf *m, int off)
>  	/* XXX: These are necessary for KAME's link-local hack */
>  	struct in6_addr all_nodes = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
>  
> -	IP6_EXTHDR_GET(mldh, struct mld_hdr *, m, off, sizeof(*mldh));
> +	IP6_EXTHDR_GET(mldh, struct mld_hdr *, &m, off, sizeof(*mldh));
>  	if (mldh == NULL) {
>  		icmp6stat_inc(icp6s_tooshort);
>  		return;
> Index: netinet6/nd6_nbr.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/nd6_nbr.c,v
> diff -u -p -r1.158 nd6_nbr.c
> --- netinet6/nd6_nbr.c	19 May 2025 06:42:53 -0000	1.158
> +++ netinet6/nd6_nbr.c	22 May 2025 07:13:58 -0000
> @@ -117,7 +117,7 @@ nd6_ns_input(struct mbuf *m, int off, in
>  	if (ifp == NULL)
>  		goto freeit;
>  
> -	IP6_EXTHDR_GET(nd_ns, struct nd_neighbor_solicit *, m, off, icmp6len);
> +	IP6_EXTHDR_GET(nd_ns, struct nd_neighbor_solicit *, &m, off, icmp6len);
>  	if (nd_ns == NULL) {
>  		icmp6stat_inc(icp6s_tooshort);
>  		if_put(ifp);
> @@ -540,7 +540,7 @@ nd6_na_input(struct mbuf *m, int off, in
>  	if (ip6->ip6_hlim != 255)
>  		goto bad;
>  
> -	IP6_EXTHDR_GET(nd_na, struct nd_neighbor_advert *, m, off, icmp6len);
> +	IP6_EXTHDR_GET(nd_na, struct nd_neighbor_advert *, &m, off, icmp6len);
>  	if (nd_na == NULL) {
>  		icmp6stat_inc(icp6s_tooshort);
>  		if_put(ifp);
> Index: netinet6/nd6_rtr.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/nd6_rtr.c,v
> diff -u -p -r1.173 nd6_rtr.c
> --- netinet6/nd6_rtr.c	19 May 2025 06:39:19 -0000	1.173
> +++ netinet6/nd6_rtr.c	22 May 2025 07:13:17 -0000
> @@ -92,7 +92,7 @@ nd6_rtr_cache(struct mbuf *m, int off, i
>  		if (IN6_IS_ADDR_UNSPECIFIED(&saddr6))
>  			goto freeit;
>  
> -		IP6_EXTHDR_GET(nd_rs, struct nd_router_solicit *, m, off,
> +		IP6_EXTHDR_GET(nd_rs, struct nd_router_solicit *, &m, off,
>  		    icmp6len);
>  		if (nd_rs == NULL) {
>  			icmp6stat_inc(icp6s_tooshort);
> @@ -109,7 +109,7 @@ nd6_rtr_cache(struct mbuf *m, int off, i
>  		if (!IN6_IS_ADDR_LINKLOCAL(&saddr6))
>  			goto bad;
>  
> -		IP6_EXTHDR_GET(nd_ra, struct nd_router_advert *, m, off,
> +		IP6_EXTHDR_GET(nd_ra, struct nd_router_advert *, &m, off,
>  		    icmp6len);
>  		if (nd_ra == NULL) {
>  			icmp6stat_inc(icp6s_tooshort);
> Index: netinet6/raw_ip6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/raw_ip6.c,v
> diff -u -p -r1.190 raw_ip6.c
> --- netinet6/raw_ip6.c	11 Mar 2025 15:31:03 -0000	1.190
> +++ netinet6/raw_ip6.c	22 May 2025 07:12:47 -0000
> @@ -147,7 +147,7 @@ rip6_input(struct mbuf **mp, int *offp, 
>  	if (proto == IPPROTO_ICMPV6) {
>  		struct icmp6_hdr *icmp6;
>  
> -		IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, *offp,
> +		IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, mp, *offp,
>  		    sizeof(*icmp6));
>  		if (icmp6 == NULL)
>  			return IPPROTO_DONE;
> Index: netinet6/route6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/route6.c,v
> diff -u -p -r1.23 route6.c
> --- netinet6/route6.c	2 Mar 2025 21:28:32 -0000	1.23
> +++ netinet6/route6.c	22 May 2025 07:17:18 -0000
> @@ -55,12 +55,11 @@ route6_input(struct mbuf **mp, int *offp
>      struct netstack *ns)
>  {
>  	struct ip6_hdr *ip6;
> -	struct mbuf *m = *mp;
>  	struct ip6_rthdr *rh;
>  	int off = *offp, rhlen;
>  
> -	ip6 = mtod(m, struct ip6_hdr *);
> -	IP6_EXTHDR_GET(rh, struct ip6_rthdr *, m, off, sizeof(*rh));
> +	ip6 = mtod(*mp, struct ip6_hdr *);
> +	IP6_EXTHDR_GET(rh, struct ip6_rthdr *, mp, off, sizeof(*rh));
>  	if (rh == NULL) {
>  		ip6stat_inc(ip6s_tooshort);
>  		return IPPROTO_DONE;
> @@ -80,7 +79,7 @@ route6_input(struct mbuf **mp, int *offp
>  			break;	/* Final dst. Just ignore the header. */
>  		}
>  		ip6stat_inc(ip6s_badoptions);
> -		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
> +		icmp6_error(*mp, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
>  			    (caddr_t)&rh->ip6r_type - (caddr_t)ip6);
>  		return (IPPROTO_DONE);
>  	}
> 

-- 
:wq Claudio