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rtadvd(8): Fix a typo in full msg receive logic

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Check against the size of the struct, not the pointer.  Previously, a message
with a cm_len between 9 and 23 (inclusive) could cause int msglen to underflow
and read(2) to be invoked with msglen size (implicitly cast to signed),
overrunning the caller-provided buffer.

All users of cm_recv() supply a stack buffer.

On the other hand, the rtadvd control socket appears to only be writable by the
owner, who is probably root.

While here, correct some types to be size_t or ssize_t.

Reported by:	Coverity
CID:		1008477
Security:	unix socket remotes may overflow stack in rtadvd
Sponsored by:	EMC / Isilon Storage Division
This commit is contained in:
Conrad Meyer 2016-05-12 03:37:17 +00:00
parent eacb70ba70
commit 96aec9a5e9
1 changed files with 6 additions and 6 deletions
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12
usr.sbin/rtadvd/control.c
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@ -59,7 +59,7 @@
int
cm_recv(int fd, char *buf)
{
int n;
ssize_t n;
struct ctrl_msg_hdr *cm;
char *msg;
struct pollfd pfds[1];
@ -98,7 +98,7 @@ cm_recv(int fd, char *buf)
}
}
if (n != sizeof(*cm)) {
if (n != (ssize_t)sizeof(*cm)) {
syslog(LOG_WARNING,
"<%s> received a too small message.", __func__);
goto cm_recv_err;
@ -123,11 +123,11 @@ cm_recv(int fd, char *buf)
"<%s> ctrl msg received: type=%d", __func__,
cm->cm_type);
if (cm->cm_len > sizeof(cm)) {
int msglen = cm->cm_len - sizeof(*cm);
if (cm->cm_len > sizeof(*cm)) {
size_t msglen = cm->cm_len - sizeof(*cm);
syslog(LOG_DEBUG,
"<%s> ctrl msg has payload (len=%d)", __func__,
"<%s> ctrl msg has payload (len=%zu)", __func__,
msglen);
for (;;) {
@ -153,7 +153,7 @@ cm_recv(int fd, char *buf)
}
break;
}
if (n != msglen) {
if (n != (ssize_t)msglen) {
syslog(LOG_WARNING,
"<%s> payload size mismatch.", __func__);
goto cm_recv_err;