Date: Mon, 25 Nov 2013 17:17:18 -0800 (PST) From: Ramon de C Valle <rdecvalle@...are.com> To: oss-security@...ts.openwall.com Subject: Re: CVE request: Kernel MSM - Memory leak in drivers/base/genlock.c ----- Original Message ----- > From: "Steven M. Christey" <coley@...re.org> > To: oss-security@...ts.openwall.com > Sent: Monday, November 25, 2013 10:57:23 PM > Subject: RE: [oss-security] CVE request: Kernel MSM - Memory leak in drivers/base/genlock.c > > Kurt said: > > >> The Genlock driver does not properly initialize all members of a > >> structure before copying it to user space. This allows a local > >> attacker to obtain potentially sensitive information from kernel > >> stack memory via ioctl system calls. > > > >This should be classified as CWE-200 Information Disclosure, "memory > >leak" refers to memory being used and not released properly, resulting > >in out of memory conditions. > > In CWE, we discourage the "memory leak" term because it has multiple meanings > and interpretations: (1) that memory is allocated but never released, or (2) > that sensitive portions of memory are accidentally disclosed to untrusted > parties. > > This request sounds like variant (2) of the varying uses of the "memory leak" > term, although Kurt's interpretation seems to be that it's about variant > (1), which further reinforces my personal desire to see that term go away > forever. > > Anyway... Note that, as this issue is described, "information disclosure" > actually results from a root cause in which certain locations are not > properly initialized. Thus CWE-665: Improper Initialization (or its child > CWE-457 Use of Uninitialized Variable) are probably more appropriate > characterizations of the core issue; in this case, it happens to lead to > memory disclosure, but in other cases, it might lead to privilege escalation > or other consequences (depending on how the uninitialized data is used.) I'd rather use "Missing Initialization of Resource (CWE-909)" to "Use of Uninitialized Resource (CWE-908)" to describe the chain of primary weaknesses. Although CWE-665 and CWE-909 seem very similar, even the examples—do we have a duplicate? > > Note that vulnerabilities can be combinations of 2 or more less-significant > errors, which in CWE are called chains or composites: > http://cwe.mitre.org/data/reports/chains_and_composites.html > > That is, just like there can be attack chains, there can be vulnerability > chains. > > As vulnerabilities become more and more complex (because the easy stuff is > slowly getting eliminated), chains and composites are likely to pose more > and more challenges for vulnerability classification in the future. The > Linux kernel is one of those places. > > For CVE assignment purposes, we generally try to classify based on the root > cause, but there is a recognition that opinions may vary widely in this > area. > > - Steve > -- Ramon de C Valle VMware (vSECR) Security Engineering Team
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