On Fri, Jan 28, 2011 at 9:23 PM, Daniel Shahaf <d...@daniel.shahaf.name> wrote:
> hwri...@apache.org wrote on Fri, Jan 28, 2011 at 20:01:35 -0000:
>> Author: hwright
>> Date: Fri Jan 28 20:01:35 2011
>> New Revision: 1064847
>>
>> URL: http://svn.apache.org/viewvc?rev=1064847&view=rev
>> Log:
>> * subversion/svnserve/serve.c
>> (log_cmd): Remove a useless check, and replace it with an assert instead.
>>
>> Modified:
>> subversion/trunk/subversion/svnserve/serve.c
>>
>> Modified: subversion/trunk/subversion/svnserve/serve.c
>> URL:
>> http://svn.apache.org/viewvc/subversion/trunk/subversion/svnserve/serve.c?rev=1064847&r1=1064846&r2=1064847&view=diff
>> ==============================================================================
>> --- subversion/trunk/subversion/svnserve/serve.c (original)
>> +++ subversion/trunk/subversion/svnserve/serve.c Fri Jan 28 20:01:35 2011
>> @@ -2008,18 +2008,17 @@ static svn_error_t *log_cmd(svn_ra_svn_c
>> revprops = NULL;
>> else if (strcmp(revprop_word, "revprops") == 0)
>> {
>> + SVN_ERR_ASSERT(revprop_items);
>> +
>> - if (revprop_items)
>
> <as far as I can tell>
>
> The 'protocol' document explicitly allows the tuple to terminate
> immediately after the 'revprops' word --- which, is the case where the
> assert would fire; therefore, either your new check violates the
> documented protocol, or the protocol documentation needs to be fixed.
>
> </as far as I can tell>
>
> Makes sense?
I guess.
The diff doesn't give much context, but the prior code was:
revprops = apr_array_make(pool, revprop_items->nelts,
sizeof(char *));
if (revprop_items)
{
...
}
Do you see the problem? The first statement *assumes* that
revprop_items isn't NULL (since it dereferences it), and then goes on
to check this same fact. In practice, I don't think we're ever see
this segfault, but it's a possibility (and may even be a remove DoS
bug if triggered correctly).
r1064847 doesn't change the fact that misbehavior still crashes the
server; it just makes that fact a bit more obvious. Improvements are
welcome.
-Hyrum
