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

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Date:   Tue, 28 May 2019 17:23:27 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     rick.p.edgecombe@...el.com
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        sparclinux@...r.kernel.org, linux-mm@...ck.org,
        netdev@...r.kernel.org, luto@...nel.org, dave.hansen@...el.com,
        namit@...are.com
Subject: Re: [PATCH v5 0/2] Fix issues with vmalloc flush flag

From: Rick Edgecombe <rick.p.edgecombe@...el.com>
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.