[SR-Users] FW: (Devel) Segmentation fault using pua_dialoginfo

[Marius Zbihlei]

On 05/16/2012 03:02 PM, Charles Chance wrote:
>>>
>>> Currently testing devel version and experiencing the following when 
>>> using pua_dialoginfo:
>>>
>>> -------------------------------------
>>>
>>> Program terminated with signal 11, Segmentation fault.
>>>
>>> #0  core_hash (t=0xb3d7e330, type=1024, ps=0xbfcc31c8) at 
>>> ../../hashes.h:279
>>>
>>> 279                     v=(*p<<24)+(p[1]<<16)+(p[2]<<8)+p[3];
>>>
>>>
Hello,
Don't know if this is related, but the statement above hides a nasty 
bug: p[1] is a char (as for the description), so is signed, shifting to 
the left 16 bits is ok, as an integral promotion takes place. The 
problem is that if p[1] is negative (-1 is 0xff), then the integral 
promotion is signed as well and is complementary of 2 (or whatever the 
implementation considers), and the shift will return another value as 
expected.

For example :
#include <stdio.h>

int main(){
     char b = 0xff;
     unsigned h = (b<<16);
     printf("%x\n", h);
     return 0;
}

will print ffff0000 instead of ff0000 as expected. Haven't calculated 
the implication of this related to the bug. An fix would be to cast p[1] 
to (unsigned char)

Cheers,
Marius




-- 
Zbihlei Marius

Head of
Linux Development Services Romania

1&1 Internet Development srl    Tel KA: 754-9152
Str Mircea Eliade 18            Tel RO: +40-31-223-9152
Sect 1, Bucuresti               mailto: marius.zbihlei at 1and1.ro
71295, Romania

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sip-router.org/pipermail/sr-users/attachments/20120516/c3cc5afa/attachment.htm>