svn commit: r279997 - head/sys/netinet

John Baldwin jhb at freebsd.org
Sat Mar 14 21:52:22 UTC 2015


On Saturday, March 14, 2015 06:11:25 PM Ian Lepore wrote:
> Author: ian
> Date: Sat Mar 14 18:11:24 2015
> New Revision: 279997
> URL: https://svnweb.freebsd.org/changeset/base/279997
> 
> Log:
>   Use sbuf_new_for_sysctl() instead of plain sbuf_new() to ensure sysctl
>   string returned to userland is nulterminated.
>   
>   PR:		195668

This is not safe.  sbuf_printf() is invoked with a lock held, so it isn't
safe for the sbuf code to do a drain here.  With sbuf_new_for_sysctl(),
any call to an sbuf routine is a potential page fault, so the handler must
either use sysctl_wire_old_buffer(), or the contents need to be output in
one go.  For this case I would prefer to use sbuf_len(sb) + 1 (or add
INCLUDENUL to the args when creating it) and leave the sole SYSCTL_OUT()
at the end.

You will want to check the one or two other places you converted for this
same issue as well.

-- 
John Baldwin


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