svn commit: r245036 - head/sys/kern
Robert Watson
rwatson at FreeBSD.org
Fri Jan 4 20:38:37 UTC 2013
On Fri, 4 Jan 2013, Mateusz Guzik wrote:
> On Fri, Jan 04, 2013 at 11:11:13AM +0000, David Xu wrote:
>> Author: davidxu
>> Date: Fri Jan 4 11:11:12 2013
>> New Revision: 245036
>> URL: http://svnweb.freebsd.org/changeset/base/245036
>>
>> Log:
>> Revert revision 244760 because strncpy pads trailing space with zero,
>> this prevents kernel data from being leaked.
>
> I think it would be better to teach strlcpy to zero-pad as well.
I'd rather we created new functions with new names that add the non-portable
zeroing behaviour -- perhaps strlpcpy() and strnpcpy(), or something equally
incomprehensible. This semantic may actually trigger bugs in code that is
correct (albeit badly written) using strncpy() and strlcpy() in a way that
never fully fills the buffer (due to some external invariant) and has an
incorrect bounds check -- and potentially trigger performance problems when
target buffers are much larger than the copied data.
Robert
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