There is a heap overflow, triggerable as root only in the IPFW firewall handling code. sys/netpfil/ipfw/ip_fw_nat.c: static int ipfw_nat_cfg(struct sockopt *sopt) { struct cfg_nat_legacy *cfg; struct nat44_cfg_nat *ucfg; struct cfg_redir_legacy *rdir; struct nat44_cfg_redir *urdir; char *buf; size_t len, len2; int error, i; len = sopt->sopt_valsize; len2 = len + 128; /* * Allocate 2x buffer to store converted structures. * new redir_cfg has shrinked, so we're sure that * new buffer size is enough. */ buf = malloc(roundup2(len, 8) + len2, M_TEMP, M_WAITOK | M_ZERO); error = sooptcopyin(sopt, buf, len, sizeof(struct cfg_nat_legacy)); The size calculation passed to `malloc` can be overflown, resulting in heap overflow on `sooptcopyin`. This function is called when the `IP_FW_NAT_CFG` command is passed to `ipfw_ctl`: int ipfw_ctl(struct sockopt *sopt) { ... /* Save original valsize before it is altered via sooptcopyin() */ valsize = sopt->sopt_valsize; opt = sopt->sopt_name; ... switch (opt) { ... case IP_FW_NAT_CFG: if (IPFW_NAT_LOADED) error = ipfw_nat_cfg_ptr(sopt); else { printf("IP_FW_NAT_CFG: %s\n", "ipfw_nat not present, please load it"); error = EINVAL; } break; `ipfw_ctl` is only called by `ipfw_ctl3`, which is available only to root processes (must have `PRIV_NETINET_IPFW` privilege): int ipfw_ctl3(struct sockopt *sopt) { ... error = priv_check(sopt->sopt_td, PRIV_NETINET_IPFW); if (error != 0) return (error); if (sopt->sopt_name != IP_FW3) return (ipfw_ctl(sopt));
This code looks like left for compatibility with old binaries. Probably it can be completely removed.