svn commit: r336031 - head/usr.bin/top

[Sean Bruno]

On 07/06/18 08:49, Ian Lepore wrote:
> On Fri, 2018-07-06 at 13:22 +0000, Sean Bruno wrote:
>> Author: sbruno
>> Date: Fri Jul  6 13:22:44 2018
>> New Revision: 336031
>> URL: https://svnweb.freebsd.org/changeset/base/336031
>>
>> Log:
>>   r336028 changed next_msg to a char * from char [] of fixed size.  Change
>>   2nd argument of vsnprintf() to get the strlen of next_msg so that the
>>   appropriate size is used.
>>   
>>   Found with gcc.
>>   
>>   /usr.bin/top/display.c: In function 'new_message':
>>   /usr.bin/top/display.c:963:31: error:
>>   argument to 'sizeof' in 'vsnprintf' call is the same expression as the
>>   destination; did you mean to provide an explicit length?
>>   [-Werror=sizeof-pointer-memaccess]
>>        vsnprintf(next_msg, sizeof(next_msg), msgfmt, args);
>>   
>>   Reviewed by:	daichi
>>
>> Modified:
>>   head/usr.bin/top/display.c
>>
>> Modified: head/usr.bin/top/display.c
>> ==============================================================================
>> --- head/usr.bin/top/display.c	Fri Jul  6 12:44:48 2018	(r336030)
>> +++ head/usr.bin/top/display.c	Fri Jul  6 13:22:44 2018	(r336031)
>> @@ -960,7 +960,7 @@ new_message(int type, const char *msgfmt, ...)
>>      va_start(args, msgfmt);
>>  
>>      /* first, format the message */
>> -    vsnprintf(next_msg, sizeof(next_msg), msgfmt, args);
>> +    vsnprintf(next_msg, strlen(next_msg), msgfmt, args);
>>  
>>      va_end(args);
>>  
>>
> 
> This fix is incorrect. The original commit that changed next_msg to a
> pointer is probably flawed enough to revert and redevelop rather than
> try a rolling set of bandaid fixes.
> 
> Whenever setup_buffer() creates a new buffer it will need to store the
> size it allocated for use in this vsnprintf() call (and maybe other
> places that write directly into next_msg without calling setup_buffer
> to reallocate it first, I didn't look). The setup_buffer_bufsiz
> variable isn't quite right as-is, because it doesn't include the
> 'addlen' value passed to setup_buffer().
> 
> -- Ian
> 
> 


Yeah, this isn't going well.  I've been poking around in it and I can't
see an quick way to do this correctly.

sean

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