On 12/13/2018 10:39 AM, Nicholas Mc Guire wrote:
> On Thu, Dec 13, 2018 at 09:14:18AM -0500, Joe Lawrence wrote:
>> On 12/13/2018 09:05 AM, Nicholas Mc Guire wrote:
>>> kzalloc() return should be checked. On dummy_alloc() failing
>>> in kzalloc() NULL should be returned.
>>>
>>> Signed-off-by: Nicholas Mc Guire <hof...@osadl.org>
>>> ---
>>>
>>> Problem was located with an experimental coccinelle script
>>>
>>> V2: returning NULL is ok but not without cleanup - thanks to
>>> Petr Mladek <pmla...@suse.com> for catching this.
>>>
>>> Patch was compile tested with: x86_64_defconfig + FTRACE=y
>>> FUNCTION_TRACER=y, EXPERT=y, LATENCYTOP=y, SAMPLES=y, SAMPLE_LIVEPATCH=y
>>> (with a number of unrelated sparse warnings on symbols not being static)
>>>
>>> Patch is against 4.20-rc6 (localversion-next is next-20181213)
>>>
>>> samples/livepatch/livepatch-shadow-mod.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/samples/livepatch/livepatch-shadow-mod.c
>>> b/samples/livepatch/livepatch-shadow-mod.c
>>> index 4c54b25..4aa8a88 100644
>>> --- a/samples/livepatch/livepatch-shadow-mod.c
>>> +++ b/samples/livepatch/livepatch-shadow-mod.c
>>> @@ -118,6 +118,10 @@ noinline struct dummy *dummy_alloc(void)
>>>
>>> /* Oops, forgot to save leak! */
>>> leak = kzalloc(sizeof(int), GFP_KERNEL);
>>> + if (!leak) {
>>> + kfree(d);
>>> + return NULL;
>>> + }
>>>
>>> pr_info("%s: dummy @ %p, expires @ %lx\n",
>>> __func__, d, d->jiffies_expire);
>>>
>>
>> Hi Nicholas,
>>
>> Thanks for finding and fixing these up... can we either squash these two
>> patches into a single commit or give them unique subject lines? Code
>> looks good (including Petr's suggested fix) otherwise.
>>
> yup - makes sense to pop it into a single patch - I assumed that this
> would not be acceptable - so I actually split it up :)
> I´ll send a V3 then.
I don't know if there is a hard rule, but I always thought that unique
subject lines were desired to avoid grep/search confusion.
As far as one or two commits, I'd prefer a single commit since these are
so small. Personal preference, you could just say that you're fixing
samples/livepatch as a whole.
>
> BTW: wanted to fix up the sparse warnings but I think thats not going
> to be that simple as the functions/structs sparse complains about
> are actually being shared:
Ok, these are welcome too, separate commit...
> CHECK samples/livepatch/livepatch-shadow-fix1.c
> samples/livepatch/livepatch-shadow-fix1.c:74:14: warning: symbol
> 'livepatch_fix1_dummy
> alloc' was not declared. Should it be static?
> samples/livepatch/livepatch-shadow-fix1.c:116:6: warning: symbol
> 'livepatch_fix1_dummy
> free' was not declared. Should it be static?
>
> CHECK samples/livepatch/livepatch-shadow-mod.c
> samples/livepatch/livepatch-shadow-mod.c:99:1: warning: symbol 'dummy_list'
> was not declared. Should it be static?
> samples/livepatch/livepatch-shadow-mod.c:100:1: warning: symbol
> 'dummy_list_mutex' was not declared. Should it be static?
> samples/livepatch/livepatch-shadow-mod.c:107:23: warning: symbol
> 'dummy_alloc' was not declared. Should it be static?
> samples/livepatch/livepatch-shadow-mod.c:132:15: warning: symbol 'dummy_free'
> was not declared. Should it be static?
> samples/livepatch/livepatch-shadow-mod.c:140:15: warning: symbol
> 'dummy_check' was not declared. Should it be static?
>
> so to clean that appropriate declarations should probably
> go into a .h file. Technically its maybe not important as this
> is not production code - it would though be nice if sample
> code is sparse/smatch/cocci clean.
>
> would it be acceptable to clean this up with an additional
> livepatch-shadow-mod.h ?
I'm not a C language expert, but as I understand it: static functions
are only a namespacing game for the compiler. So I think it is safe to
pass around and call function pointers to static functions between
compilation units. At least I see this throughout the kernel, so that
is my assumption :)
-- Joe
