Messages in this thread | | | Subject | Re: [PATCH v3 1/2] dma-mapping: Add vmap checks to dma_map_single() | From | Robin Murphy <> | Date | Fri, 11 Oct 2019 10:33:17 +0100 |
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On 2019-10-11 6:02 am, Greg Kroah-Hartman wrote: > On Thu, Oct 10, 2019 at 03:28:28PM -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..ff4e91c66f44 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 (unlikely(is_vmalloc_addr(ptr))) { >> + dev_warn_once(dev, "bad map: %zu bytes in vmalloc\n", size); > > Can we get a bit better error text here? In USB we were at least giving > people a hint as to what went wrong, "bad map" might not really make > that much sense to a USB developer as to what they needed to do to fix > this issue.
Agreed, something along the lines of "dma_map_single of vmalloc'ed buffer..." might be clearer. Also I'd be inclined to use dev_WARN_ONCE() to include a diagnostically-useful backtrace, as the existing USB code would.
Thanks, Robin.
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