ppp: Add upstream patch to fix bounds check in EAP code.

[people/pmueller/ipfire-2.x.git] / src / patches / ppp / ppp-2.4.8-pppd-fix-bounds-check-in-eap-code.patch

commit 8d7970b8f3db727fe798b65f3377fe6787575426
Author: Paul Mackerras <paulus@ozlabs.org>
Date:   Mon Feb 3 15:53:28 2020 +1100

    pppd: Fix bounds check in EAP code
    
    Given that we have just checked vallen < len, it can never be the case
    that vallen >= len + sizeof(rhostname).  This fixes the check so we
    actually avoid overflowing the rhostname array.
    
    Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
    Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

diff --git a/pppd/eap.c b/pppd/eap.c
index 94407f5..1b93db0 100644
--- a/pppd/eap.c
+++ b/pppd/eap.c
@@ -1420,7 +1420,7 @@ int len;
 		}
 
 		/* Not so likely to happen. */
-		if (vallen >= len + sizeof (rhostname)) {
+		if (len - vallen >= sizeof (rhostname)) {
 			dbglog("EAP: trimming really long peer name down");
 			BCOPY(inp + vallen, rhostname, sizeof (rhostname) - 1);
 			rhostname[sizeof (rhostname) - 1] = '\0';
@@ -1846,7 +1846,7 @@ int len;
 		}
 
 		/* Not so likely to happen. */
-		if (vallen >= len + sizeof (rhostname)) {
+		if (len - vallen >= sizeof (rhostname)) {
 			dbglog("EAP: trimming really long peer name down");
 			BCOPY(inp + vallen, rhostname, sizeof (rhostname) - 1);
 			rhostname[sizeof (rhostname) - 1] = '\0';