Messages in this thread | | | Date | Wed, 30 Oct 2019 20:26:40 +0100 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single() |
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On Wed, Oct 30, 2019 at 07:09:21PM +0100, Christoph Hellwig wrote: > On Wed, Oct 30, 2019 at 10:18:49AM +0100, Greg Kroah-Hartman wrote: > > On Tue, Oct 29, 2019 at 02:34:22PM -0700, Kees Cook wrote: > > > As we've seen from USB and other areas[1], we need to always do runtime > > > checks for DMA operating on memory regions that might be remapped. This > > > adds vmap checks (similar to those already in USB but missing in other > > > places) into dma_map_single() so all callers benefit from the checking. > > > > > > [1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb > > > > > > Suggested-by: Laura Abbott <labbott@redhat.com> > > > Signed-off-by: Kees Cook <keescook@chromium.org> > > > --- > > > include/linux/dma-mapping.h | 6 ++++++ > > > 1 file changed, 6 insertions(+) > > > > > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > > > index 4a1c4fca475a..54de3c496407 100644 > > > --- a/include/linux/dma-mapping.h > > > +++ b/include/linux/dma-mapping.h > > > @@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev) > > > static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr, > > > size_t size, enum dma_data_direction dir, unsigned long attrs) > > > { > > > + /* DMA must never operate on areas that might be remapped. */ > > > + if (dev_WARN_ONCE(dev, is_vmalloc_addr(ptr), > > > + "wanted %zu bytes mapped in vmalloc\n", size)) { > > > + return DMA_MAPPING_ERROR; > > > + } > > > > That's a very odd error string, I know if I saw it for the first time, I > > would have no idea what it meant. The USB message at least gives you a > > bit more context as to what went wrong and how to fix it. > > > > How about something like "Memory is not DMA capabable, please fix the > > allocation of it to be correct", or "non-dma-able memory was attempted > > to be mapped, but this is impossible to to" or something else. > > I've fixed the message to "rejecting DMA map of vmalloc memory" and > applied the patch.
Looks good! You can apply patch 2/2 as well if you want to take that through your tree too.
thanks,
greg k-h
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