Re: [PATCH v5 0/2] Fix issues with vmalloc flush flag

[David Miller]

From: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Date: Mon, 27 May 2019 14:10:56 -0700

> These two patches address issues with the recently added
> VM_FLUSH_RESET_PERMS vmalloc flag.
> 
> Patch 1 addresses an issue that could cause a crash after other
> architectures besides x86 rely on this path.
> 
> Patch 2 addresses an issue where in a rare case strange arguments
> could be provided to flush_tlb_kernel_range(). 

It just occurred to me another situation that would cause trouble on
sparc64, and that's if someone the address range of the main kernel
image ended up being passed to flush_tlb_kernel_range().

That would flush the locked kernel mapping and crash the kernel
instantly in a completely non-recoverable way.