[Bug 23282] New: vsnprintf(3) example promotes code which ignores error return code

[bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r@public.gmane.org]

https://bugzilla.kernel.org/show_bug.cgi?id=23282

           Summary: vsnprintf(3) example promotes code which ignores error
                    return code
           Product: Documentation
           Version: unspecified
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: man-pages
        AssignedTo: documentation_man-pages-ztI5WcYan/vQLgFONoPN62D2FQJk+8+b@public.gmane.org
        ReportedBy: graham.gower-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
        Regression: No


The example given in the vsnprintf(3) man page (release 3.31) attempts to be
backwards compatible with glibc < 2.0.6 by assuming that a negative return code
from vsnprintf indicates truncation.

If a negative return code is indicated for other reasons, the example will loop
until the process' virtual memory is exhausted.

Please see the following for an example of how a malicious user could
deliberately trigger this (potentially causing a denial of service).
http://my.opera.com/taviso/blog/2007/05/28/auditing-puzzle

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