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divert: Fix mbuf ownership confusion in div_output()

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div_output_outbound() and div_output_inbound() relied on the caller to
free the mbuf if an error occurred.  However, this is contrary to the
semantics of their callees, ip_output(), ip6_output() and
netisr_queue_src(), which always consume the mbuf.  So, if one of these
functions returned an error, that would get propagated up to
div_output(), resulting in a double free.

Fix the problem by making div_output_outbound() and div_output_inbound()
responsible for freeing the mbuf in all cases.

Reported by:	Michael Schmiedgen <schmiedgen@gmx.net>
Tested by:	Michael Schmiedgen
Reviewed by:	donner
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D30129
This commit is contained in:
Mark Johnston 2021-05-07 14:27:58 -04:00
parent 831850d8b0
commit a1fadf7de2
1 changed files with 9 additions and 8 deletions
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17
sys/netinet/ip_divert.c
View File

@ -415,17 +415,13 @@ div_output(struct socket *so, struct mbuf *m, struct sockaddr_in *sin,
}
NET_EPOCH_EXIT(et);
if (error != 0)
m_freem(m);
return (error);
}
/*
* Sends mbuf @m to the wire via ip[6]_output().
*
* Returns 0 on success, @m is consumed.
* On failure, returns error code. It is caller responsibility to free @m.
* Returns 0 on success or an errno value on failure. @m is always consumed.
*/
static int
div_output_outbound(int family, struct socket *so, struct mbuf *m)
@ -448,6 +444,7 @@ div_output_outbound(int family, struct socket *so, struct mbuf *m)
inp->inp_options != NULL) ||
((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
INP_RUNLOCK(inp);
m_freem(m);
return (EINVAL);
}
break;
@ -459,6 +456,7 @@ div_output_outbound(int family, struct socket *so, struct mbuf *m)
/* Don't allow packet length sizes that will crash */
if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
INP_RUNLOCK(inp);
m_freem(m);
return (EINVAL);
}
break;
@ -498,6 +496,7 @@ div_output_outbound(int family, struct socket *so, struct mbuf *m)
options = m_dup(inp->inp_options, M_NOWAIT);
if (options == NULL) {
INP_RUNLOCK(inp);
m_freem(m);
return (ENOBUFS);
}
}
@ -525,8 +524,7 @@ div_output_outbound(int family, struct socket *so, struct mbuf *m)
/*
* Schedules mbuf @m for local processing via IPv4/IPv6 netisr queue.
*
* Returns 0 on success, @m is consumed.
* Returns error code on failure. It is caller responsibility to free @m.
* Returns 0 on success or an errno value on failure. @m is always consumed.
*/
static int
div_output_inbound(int family, struct socket *so, struct mbuf *m,
@ -546,8 +544,10 @@ div_output_inbound(int family, struct socket *so, struct mbuf *m,
bzero(sin->sin_zero, sizeof(sin->sin_zero));
sin->sin_port = 0;
ifa = ifa_ifwithaddr((struct sockaddr *) sin);
if (ifa == NULL)
if (ifa == NULL) {
m_freem(m);
return (EADDRNOTAVAIL);
}
m->m_pkthdr.rcvif = ifa->ifa_ifp;
}
#ifdef MAC
@ -573,6 +573,7 @@ div_output_inbound(int family, struct socket *so, struct mbuf *m,
break;
#endif
default:
m_freem(m);
return (EINVAL);
}