Bug 4545 - rpc.mountd denial of service
Summary: rpc.mountd denial of service
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: nfs-server
Version: 5.2
Hardware: i386
OS: Linux
Target Milestone: ---
Assignee: David Lawrence
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 1999-08-16 16:04 UTC by ncb
Modified: 2008-05-01 15:37 UTC (History)
0 users

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 1999-08-26 22:57:33 UTC

Attachments (Terms of Use)

Description ncb 1999-08-16 16:04:07 UTC
nfs-server-2.2beta44 on Redhat 5.2, with kernel 2.2.9.

My /etc/exports looks like this:
/hj4    @all-cc(rw)

We've got some hosts that are not in the all-cc netgroup,
and should be denied access to /hj4.  rpc.mountd does deny
the mount to these systems, but suffers a SIGSEGV in the

After inspecting auth.c:auth_unknown_clientbyaddr() this
behavior seems not to be strictly a YP problem, but rather
any unauthorized host requesting services from mountd.

Here is a (quite simple) patch:

*** nfs-server-2.2beta43/auth.c.OLD     Sat Aug 14 21:39:56
--- nfs-server-2.2beta43/auth.c Sat Aug 14 21:40:18 1999
*** 479,485 ****
                auth_add_mountlist(ncp, cp->m, 0);

!       auth_sort_mountlist(ncp->m);
        return ncp;

--- 479,485 ----
                auth_add_mountlist(ncp, cp->m, 0);

!       if(ncp) auth_sort_mountlist(ncp->m);
        return ncp;

Neil Bright
Computing and Networking Services
College of Computing
Georgia Institute of Technology

Comment 1 ncb 1999-08-19 18:33:59 UTC
Sorry, forgot to mention this isn't a problem with knfsd in 6.0.

Comment 2 Jeff Johnson 1999-08-26 22:57:59 UTC
Fixed in nfs-server-2.2beta44-2. Thanks for the patch.

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