Bug 253926 (CVE-2007-4133)

Summary:	CVE-2007-4133 prio_tree unit kernel panic
Product:	[Other] Security Response	Reporter:	Marcel Holtmann <holtmann>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	low
Version:	unspecified	CC:	anton, kernel-mgr, konradr, kreilly, kseifried, tao
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-09-28 20:31:44 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	253929, 253930
Bug Blocks:

Description Marcel Holtmann 2007-08-22 22:56:20 UTC

hugetlb_vmtruncate_list was misconverted to prio_tree: its prio_tree is in units
of PAGE_SIZE (PAGE_CACHE_SIZE) like any other, not HPAGE_SIZE (whereas its
radix_tree is kept in units of HPAGE_SIZE, otherwise slots would be absurdly
sparse).

At first I thought the error benign, just calling __unmap_hugepage_range on more
vmas than necessary; but on 32-bit machines, when the prio_tree is searched
correctly, it happens to ensure the v_offset calculation won't overflow.  As it
stood, when truncating at or beyond 4GB, it was liable to discard pages COWed
from lower offsets; or even to clear pmd entries of preceding vmas, triggering
exit_mmap's BUG_ON(nr_ptes).

Comment 8 Kurt Seifried 2011-09-28 20:31:44 UTC

All children bugs have been closed, parent is no longer needed.