[PATCH 4/4] rtems-debugger-target.c: Fix Coverity Dereference before null check

[Chris Johns]

On 12/2/21 8:03 am, Joel Sherrill wrote:
> On Thu, Feb 11, 2021, 3:00 PM Chris Johns <chrisj at rtems.org
> <mailto:chrisj at rtems.org>> wrote:
> 
>     On 12/2/21 7:27 am, Ryan Long wrote:
>     > Fixes CID #1468682 where target is dereferenced before it has been
>     > checked as to whether it is null or not in the
>     > rtems_debugger_target_swbreak_control function.
>     > ---
>     >  cpukit/libdebugger/rtems-debugger-target.c | 5 +++--
>     >  1 file changed, 3 insertions(+), 2 deletions(-)
>     >
>     > diff --git a/cpukit/libdebugger/rtems-debugger-target.c
>     b/cpukit/libdebugger/rtems-debugger-target.c
>     > index e495170..3726a6c 100644
>     > --- a/cpukit/libdebugger/rtems-debugger-target.c
>     > +++ b/cpukit/libdebugger/rtems-debugger-target.c
>     > @@ -171,17 +171,18 @@ int
>     >  rtems_debugger_target_swbreak_control(bool insert, DB_UINT addr, DB_UINT
>     kind)
>     >  {
>     >    rtems_debugger_target*         target = rtems_debugger->target;
>     > -  rtems_debugger_target_swbreak* swbreaks = target->swbreaks.block;

rtems_debugger_target_swbreak* swbreaks;

>     >    size_t                         swbreak_size;
>     >    uint8_t*                       loc = (void*) addr;
>     >    size_t                         i;
>     >    int                            r;
>     > 
>     > -  if (target == NULL || swbreaks == NULL || kind !=
>     target->breakpoint_size) {
>     > +  if (target == NULL || target->swbreaks.block == NULL ||
>     > +      kind != target->breakpoint_size) {
>     >      errno = EIO;
>     >      return -1;
>     >    }
>     > 
>     > +  rtems_debugger_target_swbreak* swbreaks = target->swbreaks.block;

swbreaks = target->swbreaks.block;

> 
>     The debug server does not declare local vars in the body of functions. I would
>     prefer the this code base stays that way if that is OK?
> 
> 
> Then how do you want to address the issue identified by Coverity
> 

As above. Like us old timers always did with C :) :).

As someone who likes and uses C++ I prefer C to clearly have the local vars at
the start of the block.

Chris