Messages in this thread | | | Subject | Re: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var | From | Igor Stoppa <> | Date | Wed, 7 Mar 2018 15:18:16 +0200 |
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On 06/03/18 19:20, J Freyensee wrote:
> On 2/28/18 12:06 PM, Igor Stoppa wrote:
[...]
>> void __init lkdtm_perms_init(void); >> void lkdtm_WRITE_RO(void); >> void lkdtm_WRITE_RO_AFTER_INIT(void); >> +void lkdtm_WRITE_RO_PMALLOC(void); > > Does this need some sort of #ifdef too?
Not strictly. It's just a function declaration. As long as it is not used, the linker will not complain. The #ifdef placed around the use and definition is sufficient, from a correctness perspective.
But it's a different question if there is any standard in linux about hiding also the declaration.
I am not very fond of #ifdefs, so when I can I try to avoid them.
>> + pr_info("attempting bad pmalloc write at %p\n", i); >> + *i = 0; > > OK, now I'm on the right version of this patch series, same comment > applies. I don't get the local *i assignment at the end of the > function, but seems harmless.
Because that's the whole point of the function: prove that pmalloc protection works (see the message in the pr_info one line above).
The function is supposed to do:
* create a pool * allocate memory from it * protect it * try to alter it (and crash)
*i = 0; performs the last step
-- igor
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