CVE-2016-4913: Infoleak
A vulnerability was found in the Linux kernel. Payloads of NM entries are not supposed to contain NUL. When such entry is processed, only the part prior to the first NUL goes into the concatenation (i.e. the directory entry name being encoded by a bunch of NM entries). The process stops when the amount collected so far + the claimed amount in the current NM entry exceed 254.
However, the value returned as the total length is the sum of claimed sizes, not the actual amount collected. And that can grow pretty large - not unlimited, since you'd need to put CE entries in between to be able to get more than the maximum that could be contained in one isofs directory entry / continuation chunk and the process stops once it had encountered 32 CEs, but you can get about 8Kb easily. And that's what will be passed to readdir callback as the name length. 8Kb copytouser() from a buffer allocated by getfreepage()
References, CVE-ID request and response:
http://seclists.org/oss-sec/2016/q2/363
http://seclists.org/oss-sec/2016/q2/365
Upstream fix:
https://git.kernel.org/linus/99d825822eade8d827a1817357cbf3f889a552d6
Other sources
The getrockridgefilename function in fs/isofs/rock.c in the Linux kernel before 4.5.5 mishandles NM (aka alternate name) entries containing \0 characters, which allows local users to obtain sensitive information from kernel memory or possibly have unspecified other impact via a crafted isofs filesystem.
— Launchpad
Affected Software
Remediation
Patch Available
Patch Available
Event History
Frequently Asked Questions
What is the severity of CVE-2016-4913?
CVE-2016-4913 has a moderate severity rating due to its potential impact on Linux kernel systems.
How do I fix CVE-2016-4913?
To fix CVE-2016-4913, update the Linux kernel to version 5.10.223-1 or later.
What versions of Linux are affected by CVE-2016-4913?
CVE-2016-4913 affects several versions including Ubuntu 12.04, 14.04, 15.10, 16.04, and multiple Linux kernel versions up to 4.4.
What components are impacted by CVE-2016-4913?
CVE-2016-4913 impacts the Linux kernel's handling of certain network management entries.
Is there a known exploit for CVE-2016-4913?
As of now, there are no publicly disclosed exploits specifically targeting CVE-2016-4913.