Experimental Physics and
Industrial Control System

[email protected] (Jeff Hill) · Thu, 28 Jan 1999 12:08:50 -0700

All:

A bug has been found by Stephanie Allison in the GDD portion of the C++ based CA server libraries.
It does not have any impact on the IOCs, or any of the client side tools. Specifically there will 
be no impact unless you use server side tools based on the new C++ based server library 
at your site.

Symptoms:
Probably none.

Description of bug 1:
When a client fetched data type dbr_gr_enum a 40 character string was copied into a 26 character 
string. The bug was probably benign unless the maximum number of strings in the dbr_gr_enum structure
were used and the message was at the very end of the CA message buffer.

Description of bug 2:
When a dbr_gr_enum structure is copied into a GDD the code would strncpy() a 40 character string out of a 
26 character string. The bug was probably benign unless the incoming string was not null terminated.

Thanks to Stephanie Allison (and some clever error checking in the DEC C++ compiler) for bringing this 
to our attention.

Here are the changes that I committed to CVS:

retrieving revision 1.20
diff -r1.20 dbMapper.cc
1024,1026c1024,1026
<               strncpy(str[i].fixed_string,&(db->strs[i][0]),
<                       sizeof(aitFixedString));
<               str[i].fixed_string[sizeof(aitFixedString)-1u] = '\0';
---
>               unsigned minl = min (sizeof(aitFixedString), MAX_ENUM_STRING_SIZE) - 1;
>               strncpy (str[i].fixed_string,&(db->strs[i][0]), minl);
>               memset (&str[i].fixed_string[minl], '\0', sizeof(aitFixedString)-minl);
1095,1096c1095,1096
<                               sizeof(aitFixedString));
<                       db->strs[i][sizeof(aitFixedString)-1u] = '\0';
---
>                               MAX_ENUM_STRING_SIZE);
>                       db->strs[i][MAX_ENUM_STRING_SIZE-1u] = '\0';

I didnt see any other instances.

Jeff

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System