Date: Thu, 22 Jun 2000 09:52:35 +0400 From: "Oles' Hnatkevych" <gnut@fc.kiev.ua> To: freebsd-bugs@freebsd.org Cc: brian@Awfulhak.org Subject: bug in PPP code Message-ID: <13411.000622@fc.kiev.ua>
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Hello!
PPP code does not properly handle the information about
interfaces, resulting in routing lost to some peers
and complaining about inability to delete address from
interface (though it does not belong to that interface).
Some of you may have seen me in freebsd-questions complaining
about "Warning" that issued PPP telling that can not removed
address from interface.
Finally the bug in PPP source code was found. The bug is
difficult to spot because not many of you use more than
10 tunnel devices simultaneously.
The bug is in iface.c: look at the lines below and check out the
quoted line
while (ptr < end && iface == NULL) {
ifm = (struct if_msghdr *)ptr; /* On if_msghdr */
if (ifm->ifm_type != RTM_IFINFO)
break;
dl = (struct sockaddr_dl *)(ifm + 1); /* Single _dl at end */
>> if (!strncmp(name, dl->sdl_data, dl->sdl_nlen)) {
iface = (struct iface *)malloc(sizeof *iface);
if (iface == NULL) {
fprintf(stderr, "iface_Create: malloc: %s\n", strerror(errno));
return NULL;
}
Suppose the tun30 has been chosen and in the loop
we've received the information about tun3. The strncmp function
WILL return 0, because tun3 = tun30, comparing just first 4
characters, which is the length of "tun3" (dl->sdl_nlen). The
result of this that internal PPP structure that contains
information about interface at the beginning has wrong
data about it's current addresses (in example tun3 address).
And again, the route to this address is removed from routing
table, but kernel can not delete this address from interface
cause it does not belong to it.
We've removed the letter 'n' from the function name and
it's last argument and are now happy ;)
I believe that strncmp may cause some other errors, since
it is used serveral times in the PPP source code, and
I'm not bothering to find out if it is used properly.
With best wishes, Oles' Hnatkevych, http://gnut.kiev.ua, gnut@fc.kiev.ua
Finance & Credit Banking Corporation, Kyiv, Ukraine.
Industrialnaya str. 27 +380 44 2417190
Artema str. 60, +380 44 4906877
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