Bug 608583 (CVE-2010-2248)

Summary: CVE-2010-2248 kernel: cifs: Fix a kernel BUG with remote OS/2 server
Product: [Other] Security Response Reporter: Eugene Teo (Security Response) <eteo>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: bhu, bressers, dhoward, jolsa, lgoncalv, lwang, plyons, rkhan, steved, vgoyal, williams
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-06-10 22:32:34 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 608584, 608585, 608586, 608587, 608588    
Bug Blocks:    

Description Eugene Teo (Security Response) 2010-06-28 08:19:38 UTC
Description of problem:
While chasing a bug report involving a OS/2 server, I noticed the server sets pSMBr->CountHigh to a incorrect value even in case of normal writes. This results in 'nbytes' being computed wrongly and triggers a kernel BUG at mm/filemap.c.
    void iov_iter_advance(struct iov_iter *i, size_t bytes)
            BUG_ON(i->count < bytes);    <--- BUG here
Why the server is setting 'CountHigh' is not clear but only does so after writing 64k bytes. Though this looks like the server bug, the client side crash may not be acceptable.
The workaround is to mask off high 16 bits if the number of bytes written as returned by the server is greater than the bytes requested by the client.

Upstream commit:
http://git.kernel.org/linus/6513a81e9325d712f1bfb9a1d7b750134e49ff18 (v2.6.34-rc4)

Comment 4 Eugene Teo (Security Response) 2010-06-29 02:22:43 UTC

This issue did not affect the version of Linux kernel as shipped with Red Hat Enterprise Linux 3 as it did not have support for CIFS. Future updates in Red Hat Enterprise Linux 4, 5, and Red Hat Enterprise MRG may address this flaw.

Comment 5 errata-xmlrpc 2010-08-05 16:47:51 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 4

Via RHSA-2010:0606 https://rhn.redhat.com/errata/RHSA-2010-0606.html

Comment 6 errata-xmlrpc 2010-08-10 18:01:36 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5

Via RHSA-2010:0610 https://rhn.redhat.com/errata/RHSA-2010-0610.html

Comment 7 errata-xmlrpc 2010-08-17 15:53:02 UTC
This issue has been addressed in following products:

  MRG for RHEL-5

Via RHSA-2010:0631 https://rhn.redhat.com/errata/RHSA-2010-0631.html