[PATCH 4/4] rtems-debugger-target.c: Fix Coverity Dereference before null check
Joel Sherrill
joel at rtems.org
Thu Feb 11 21:33:19 UTC 2021
On Thu, Feb 11, 2021 at 3:29 PM Chris Johns <chrisj at rtems.org> wrote:
> On 12/2/21 8:16 am, Gedare Bloom wrote:
> > On Thu, Feb 11, 2021 at 2:00 PM Chris Johns <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;
> >>> 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;
> >>
> >> 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?
> >>
> > Good catch. This is a holdover from ANSI C that we should generally
> > adhere to in RTEMS cpukit code for historical reasons.
>
> Yes I agree. I understand and accept this is a personal thing and I stated
> my
> preference in the other post.
>
No. I missed that you wanted the variable at the top of scope. I agree that
tighter scoping is more a C++ thing than a C thing. I was looking for
something
more complicated.
>
> I use this feature judicially in C++ where I think it is more important to
> do
> so. In C++ a variable can be declared in a number of ways and places and I
> feel
> being consistent aids readability. Compilers are smart enough to figure
> out when
> a variable become active and we do not need to help.
>
It is nice when a temporary variable is only used inside an if or loop.
--joel
>
> Chris
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