Last updated 24 July 2024
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
In the marksourcechains function (net/ipv4/netfilter/iptables.c) it is possible for a user-supplied iptentry structure to have a large nextoffset field. This field is not bounds checked prior to writing a counter value at the supplied offset.
Proposed fix:
patch v1 message: http://marc.info/?l=netfilter-devel&m=145757134822741&w=2 patch v2 thread: http://marc.info/?t=145757149500006&r=1&w=2
patch v2 message: http://marc.info/?l=netfilter-devel&m=145762719008418&w=2 patch v2 thread: (none yet) http://marc.info/?l=netfilter-devel&r=4&b=201603&w=2
CVE request and assignment:
http://seclists.org/oss-sec/2016/q1/581 http://seclists.org/oss-sec/2016/q1/619
Audit done by netfilter team found several related bugs, patches to better validate rulesets are currently queued in pablos nf-next tree upstream (use "parent" link to cycle to next one - there are 17 additional patches):
https://git.kernel.org/cgit/linux/kernel/git/pablo/nf-next.git/commit/?id=d7591f0c41ce3e67600a982bab6989ef0f07b3ce