Re: [0/8] target-iSCSI: Adjustments for several function implementations

2018-02-23 Thread SF Markus Elfring 
>> Can a passed null pointer really work in this function?
>>
>> https://elixir.bootlin.com/linux/v4.16-rc2/source/include/crypto/hash.h#L684
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/crypto/hash.h?id=0f9da844d87796ac31b04e81ee95e155e9043132#n751
>>
>> static inline struct crypto_tfm *crypto_shash_tfm(struct crypto_shash *tfm)
>> {
>>  return >base;
>> }
> 
> Yes.  It's not a dereference,

Do any processors treat the zero address still special there?


> it's just doing pointer math to get the address.

Can eventually happen anything unexpected?


Can it be nicer to avoid such a software behaviour concern generally
just by adjusting a few jump labels (as I proposed it)?

Regards,
Markus

Re: [0/8] target-iSCSI: Adjustments for several function implementations

2018-02-23 Thread Dan Carpenter 
On Fri, Feb 23, 2018 at 10:06:16AM +0100, SF Markus Elfring wrote:
> > Calling crypto_free_shash(NULL) is actually fine.
> 
> Really?
> 
> 
> > It doesn't dereference the parameter, it just does pointer math on it in
> > crypto_shash_tfm() and returns if it's NULL in crypto_destroy_tfm().
> 
> Can a passed null pointer really work in this function?
> 
> https://elixir.bootlin.com/linux/v4.16-rc2/source/include/crypto/hash.h#L684
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/crypto/hash.h?id=0f9da844d87796ac31b04e81ee95e155e9043132#n751
> 
> static inline struct crypto_tfm *crypto_shash_tfm(struct crypto_shash *tfm)
> {
>   return >base;
> }

Yes.  It's not a dereference, it's just doing pointer math to get the
address.

regards,
dan carpenter

Re: [0/8] target-iSCSI: Adjustments for several function implementations

2018-02-23 Thread SF Markus Elfring 
> Calling crypto_free_shash(NULL) is actually fine.

Really?


> It doesn't dereference the parameter, it just does pointer math on it in
> crypto_shash_tfm() and returns if it's NULL in crypto_destroy_tfm().

Can a passed null pointer really work in this function?

https://elixir.bootlin.com/linux/v4.16-rc2/source/include/crypto/hash.h#L684
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/crypto/hash.h?id=0f9da844d87796ac31b04e81ee95e155e9043132#n751

static inline struct crypto_tfm *crypto_shash_tfm(struct crypto_shash *tfm)
{
return >base;
}


Regards,
Markus

Re: [0/8] target-iSCSI: Adjustments for several function implementations

2018-02-23 Thread SF Markus Elfring 
> You're 1/8 patch had an actual bug fix hidden amongst the style churn.

It showed the general possibility to adjust the source code structure
for the function “chap_server_compute_md5” also because of the usage
of the single jump label “out” before.


> I don't see any such fixes in the other patches.

This view is appropriate.

Further update steps show different transformation possibilities.


> My opinion from https://www.spinics.net/lists/target-devel/msg16342.html
> hasn't changed. FWIW, I'd prefer to see LIO adopt a policy similar to:
> https://btrfs.wiki.kernel.org/index.php/Developer%27s_FAQ#How_not_to_start

It seems that you express a few aspects for general change resistance.
Will the circumstances evolve for similar software improvements?

Regards,
Markus