svn commit: r358013 - in head/sys: net netinet netinet6

[Gleb Smirnoff]

On Mon, Feb 17, 2020 at 09:46:32AM +0000, Hans Petter Selasky wrote:
H> Author: hselasky
H> Date: Mon Feb 17 09:46:32 2020
H> New Revision: 358013
H> URL: https://svnweb.freebsd.org/changeset/base/358013
H> 
H> Log:
H>   Fix kernel panic while trying to read multicast stream.
H>   
H>   When VIMAGE is enabled make sure the "m_pkthdr.rcvif" pointer is set
H>   for all mbufs being input by the IGMP/MLD6 code. Else there will be a
H>   NULL-pointer dereference in the netisr code when trying to set the
H>   VNET based on the incoming mbuf. Add an assert to catch this when
H>   queueing mbufs on a netisr to make debugging of similar cases easier.
H>   
H>   Found by:	Vladislav V. Prodan
H>   PR:		244002
H>   Reviewed by:	bz@
H>   MFC after:	1 week
H>   Sponsored by:	Mellanox Technologies
H> 
H> Modified:
H>   head/sys/net/netisr.c
H>   head/sys/netinet/igmp.c
H>   head/sys/netinet6/mld6.c
H> 
H> Modified: head/sys/net/netisr.c
H> ==============================================================================
H> --- head/sys/net/netisr.c	Mon Feb 17 01:59:55 2020	(r358012)
H> +++ head/sys/net/netisr.c	Mon Feb 17 09:46:32 2020	(r358013)
H> @@ -1056,6 +1056,8 @@ netisr_queue_src(u_int proto, uintptr_t source, struct
H>  	if (m != NULL) {
H>  		KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__,
H>  		    cpuid));
H> +		VNET_ASSERT(m->m_pkthdr.rcvif != NULL,
H> +		    ("%s:%d rcvif == NULL: m=%p", __func__, __LINE__, m));
H>  		error = netisr_queue_internal(proto, m, cpuid);
H>  	} else
H>  		error = ENOBUFS;
H> 
H> Modified: head/sys/netinet/igmp.c
H> ==============================================================================
H> --- head/sys/netinet/igmp.c	Mon Feb 17 01:59:55 2020	(r358012)
H> +++ head/sys/netinet/igmp.c	Mon Feb 17 09:46:32 2020	(r358013)
H> @@ -303,6 +303,7 @@ igmp_save_context(struct mbuf *m, struct ifnet *ifp)
H>  #ifdef VIMAGE
H>  	m->m_pkthdr.PH_loc.ptr = ifp->if_vnet;
H>  #endif /* VIMAGE */
H> +	m->m_pkthdr.rcvif = ifp;
H>  	m->m_pkthdr.flowid = ifp->if_index;
H>  }
H>  
H> 
H> Modified: head/sys/netinet6/mld6.c
H> ==============================================================================
H> --- head/sys/netinet6/mld6.c	Mon Feb 17 01:59:55 2020	(r358012)
H> +++ head/sys/netinet6/mld6.c	Mon Feb 17 09:46:32 2020	(r358013)
H> @@ -283,6 +283,7 @@ mld_save_context(struct mbuf *m, struct ifnet *ifp)
H>  #ifdef VIMAGE
H>  	m->m_pkthdr.PH_loc.ptr = ifp->if_vnet;
H>  #endif /* VIMAGE */
H> +	m->m_pkthdr.rcvif = ifp;
H>  	m->m_pkthdr.flowid = ifp->if_index;
H>  }

This functions igmp_save_context() and mld_save_context() were clearly
designed to avoid dereferencing an ifnet pointer after a packet has been
queued and dequeued on IGMP/MLD internal queue.

This patch now replicates the exactly same problem but with netisr
queue. Of course netisr not always queues, sometimes dispatches
directly, but it may do queue.

I think same thing needs to be done to netisr internally - don't
dereference m->m_pkthdr.rcvif on dequeued packets, but store the
vnet info in the m->m_pkthdr.PH_loc.ptr before queueing.

-- 
Gleb Smirnoff