Messages in this thread | | | Date | Wed, 29 Jan 2020 16:43:30 +0000 (UTC) | From | Christopher Lameter <> | Subject | Re: [kernel-hardening] [PATCH 09/38] usercopy: Mark kmalloc caches as usercopy caches |
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On Tue, 28 Jan 2020, Kees Cook wrote:
> > On the other hand not marking the DMA caches still seems questionable. > > My understanding is that exposing DMA memory to userspace copies can > lead to unexpected results, especially for misbehaving hardware, so I'm > not convinced this is a generically bad hardening choice.
"DMA" memory (and thus DMA caches) have nothing to do with DMA. Its a legacy term. "DMA Memory" is memory limited to a certain physical address boundary (old restrictions on certain devices only supporting a limited number of address bits).
DMA can be done to NORMAL memory as well.
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