diff options
| author | Shigeru Yoshida <syoshida@redhat.com> | 2026-03-15 17:27:49 +0900 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2026-03-16 11:29:20 +0100 |
| commit | 6f770b73d0311a5b099277653199bb6421c4fed2 (patch) | |
| tree | 07e1cfb1ca4ac749e1617856e24220ce5cbabaea /kernel/dma | |
| parent | d5b5e8149af0f5efed58653cbebf1cb3258ce49a (diff) | |
dma: swiotlb: add KMSAN annotations to swiotlb_bounce()
When a device performs DMA to a bounce buffer, KMSAN is unaware of
the write and does not mark the data as initialized. When
swiotlb_bounce() later copies the bounce buffer back to the original
buffer, memcpy propagates the uninitialized shadow to the original
buffer, causing false positive uninit-value reports.
Fix this by calling kmsan_unpoison_memory() on the bounce buffer
before copying it back in the DMA_FROM_DEVICE path, so that memcpy
naturally propagates initialized shadow to the destination.
Suggested-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/CAG_fn=WUGta-paG1BgsGRoAR+fmuCgh3xo=R3XdzOt_-DqSdHw@mail.gmail.com/
Fixes: 7ade4f10779c ("dma: kmsan: unpoison DMA mappings")
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260315082750.2375581-1-syoshida@redhat.com
Diffstat (limited to 'kernel/dma')
| -rw-r--r-- | kernel/dma/swiotlb.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index d8e6f1d889d5..9fd73700ddcf 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -30,6 +30,7 @@ #include <linux/gfp.h> #include <linux/highmem.h> #include <linux/io.h> +#include <linux/kmsan-checks.h> #include <linux/iommu-helper.h> #include <linux/init.h> #include <linux/memblock.h> @@ -901,10 +902,19 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size local_irq_save(flags); page = pfn_to_page(pfn); - if (dir == DMA_TO_DEVICE) + if (dir == DMA_TO_DEVICE) { + /* + * Ideally, kmsan_check_highmem_page() + * could be used here to detect infoleaks, + * but callers may map uninitialized buffers + * that will be written by the device, + * causing false positives. + */ memcpy_from_page(vaddr, page, offset, sz); - else + } else { + kmsan_unpoison_memory(vaddr, sz); memcpy_to_page(page, offset, vaddr, sz); + } local_irq_restore(flags); size -= sz; @@ -913,8 +923,15 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size offset = 0; } } else if (dir == DMA_TO_DEVICE) { + /* + * Ideally, kmsan_check_memory() could be used here to detect + * infoleaks (uninitialized data being sent to device), but + * callers may map uninitialized buffers that will be written + * by the device, causing false positives. + */ memcpy(vaddr, phys_to_virt(orig_addr), size); } else { + kmsan_unpoison_memory(vaddr, size); memcpy(phys_to_virt(orig_addr), vaddr, size); } } |