Bug 20223

Summary: libio: Implement vtable validation
Product: glibc Reporter: Florian Weimer <fweimer>
Component: libcAssignee: Florian Weimer <fweimer>
Status: RESOLVED DUPLICATE    
Severity: normal CC: drepper.fsp
Priority: P2 Flags: fweimer: security-
Version: 2.24   
Target Milestone: ---   
Host: Target:
Build: Last reconfirmed:

Description Florian Weimer 2016-06-08 12:24:47 UTC 
There is a well-documented exploit technique which involves writing pointers to custom vtables for the stdio streams, thus hijacking code execution.

By default, we should reject invalid vtables.  For backwards compatibility with really old binaries (from the GCC 2.95 era), we need to provide some way to disable this hardening on demand.

Further background information about the libio ABI is available here:

  https://sourceware.org/glibc/wiki/LibioVtables

This is just additional security hardening (despite existing exploits), so I'm flagging this issue as security-.
Comment 1 Florian Weimer 2016-06-09 12:22:43 UTC 
Not sure what I was thinking ...

*** This bug has been marked as a duplicate of bug 20191 ***