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Date: Thu, 2 Nov 2017 11:11:10 -0700
From: Petr NejedlĂ˝ <>
To: <>
Subject: Re: Re: [PATCH V8 0/2] printk: hash addresses
 printed with %p

On 11/02/2017 09:04 AM, Sergey Senozhatsky wrote:
>>> hm... just a huge pile of if's
>>> 	if (is_vmalloc_addr(addr))
>>> 		do_hashing(addr);
>>> 	else if (__module_address(addr))
>>> 		do_hashing(addr);
>>> 	else if (is_kernel(addr) || is_kernel_inittext(addr))
>>> 	...
>>> but that's going to be really messy and "iffy".
>> This is the only suggestion we have so far.
> well... one more: check if we can safely dereference it. if so
> it's a pointer, probably :)
> 	if (!probe_kernel_address(addr, p))
> 		do_hashing(addr);
None of that would fly - you'd open a side channel.
Just find a place where kernel prints userland provided value with %x
(quite easy I suppose) and check if it got hashed. A trivial and 
way to probe the kernel address space....


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