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o Pass our negotiated number of VJ slots into

Browse Source 
sl_uncompress_tcp() and drop packets with
  slot numbers that are out of range.
o Drop packets that want to use a slot that still
  has an IP header length of 0 (ie, the requested
  slot number is bogus again).

Without this code, if the other side mis-behaves (and
sends us garbage slot numbers), we happily ``adjust''
a memset(..., '\0', ...) TCP/IP header and promptly
cr*p all over the stack before returning.... quickly
followed by a SIGBUS.

Dodgy ISP used by, and help locating the problem from: jmz
Problem also seen by: Mourad de Riche <omnibus@image.dk>

There's still a link lockup after this happens, but my
bets are on the other side (who has already started sending
rubbish) being to blame.
This commit is contained in:
Brian Somers 1998-06-14 00:56:13 +00:00
parent 396ffb2e6b
commit 42c57c8682
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=36960
3 changed files with 15 additions and 10 deletions
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13
usr.sbin/ppp/slcompress.c
View File

@ -17,7 +17,7 @@
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* $Id: slcompress.c,v 1.15.2.11 1998/05/01 19:25:59 brian Exp $
* $Id: slcompress.c,v 1.16 1998/05/21 21:48:27 brian Exp $
*
* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
* - Initial distribution.
@ -402,8 +402,8 @@ sl_compress_tcp(struct mbuf * m,
int
sl_uncompress_tcp(u_char ** bufp, int len, u_int type,
struct slcompress *comp, struct slstat *slstat)
sl_uncompress_tcp(u_char ** bufp, int len, u_int type, struct slcompress *comp,
struct slstat *slstat, int max_state)
{
register u_char *cp;
register u_int hlen, changes;
@ -415,7 +415,7 @@ sl_uncompress_tcp(u_char ** bufp, int len, u_int type,
case TYPE_UNCOMPRESSED_TCP:
ip = (struct ip *) * bufp;
if (ip->ip_p >= MAX_VJ_STATES)
if (ip->ip_p > max_state)
goto bad;
cs = &comp->rstate[comp->last_recv = ip->ip_p];
comp->flags &= ~SLF_TOSS;
@ -455,8 +455,9 @@ sl_uncompress_tcp(u_char ** bufp, int len, u_int type,
* Make sure the state index is in range, then grab the state. If we have
* a good state index, clear the 'discard' flag.
*/
if (*cp >= MAX_VJ_STATES || comp->last_recv == 255)
if (*cp > max_state || comp->last_recv == 255) {
goto bad;
}
comp->flags &= ~SLF_TOSS;
comp->last_recv = *cp++;
@ -474,6 +475,8 @@ sl_uncompress_tcp(u_char ** bufp, int len, u_int type,
}
cs = &comp->rstate[comp->last_recv];
hlen = cs->cs_ip.ip_hl << 2;
if (hlen == 0)
goto bad; /* We've been pointed at a not-yet-used slot ! */
th = (struct tcphdr *) & ((u_char *) & cs->cs_ip)[hlen];
th->th_sum = htons((*cp << 8) | cp[1]);
cp += 2;

4
usr.sbin/ppp/slcompress.h
View File

@ -16,7 +16,7 @@
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* $Id: slcompress.h,v 1.10.2.5 1998/05/01 19:26:00 brian Exp $
* $Id: slcompress.h,v 1.11 1998/05/21 21:48:30 brian Exp $
*
* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
* - Initial distribution.
@ -145,5 +145,5 @@ extern void sl_compress_init(struct slcompress *, int);
extern u_char sl_compress_tcp(struct mbuf *, struct ip *, struct slcompress *,
struct slstat *, int);
extern int sl_uncompress_tcp(u_char **, int, u_int, struct slcompress *,
struct slstat *);
struct slstat *, int);
extern int sl_Show(struct cmdargs const *);

8
usr.sbin/ppp/vjcomp.c
View File

@ -17,7 +17,7 @@
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* $Id: vjcomp.c,v 1.16.2.17 1998/05/04 03:00:09 brian Exp $
* $Id: vjcomp.c,v 1.17 1998/05/21 21:49:06 brian Exp $
*
* TODO:
*/
@ -106,7 +106,8 @@ VjUncompressTcp(struct ipcp *ipcp, struct mbuf * bp, u_char type)
* space for uncompression job.
*/
bufp = MBUF_CTOP(bp);
len = sl_uncompress_tcp(&bufp, len, type, &ipcp->vj.cslc, &ipcp->vj.slstat);
len = sl_uncompress_tcp(&bufp, len, type, &ipcp->vj.cslc, &ipcp->vj.slstat,
(ipcp->my_compproto >> 8) & 255);
if (len <= 0) {
mbuf_Free(bp);
bp = NULL;
@ -124,7 +125,8 @@ VjUncompressTcp(struct ipcp *ipcp, struct mbuf * bp, u_char type)
rlen = len;
bufp = work + MAX_HDR;
bp = mbuf_Read(bp, bufp, rlen);
len = sl_uncompress_tcp(&bufp, olen, type, &ipcp->vj.cslc, &ipcp->vj.slstat);
len = sl_uncompress_tcp(&bufp, olen, type, &ipcp->vj.cslc, &ipcp->vj.slstat,
(ipcp->my_compproto >> 8) & 255);
if (len <= 0) {
mbuf_Free(bp);
return NULL;