On Tue, Nov 25, 2025 at 05:11:18PM -0800, Alex Mastro wrote:

fill_sg_entry() splits large DMA buffers into multiple scatter-gather entries, each holding up to UINT_MAX bytes. When calculating the DMA address for entries beyond the second one, the expression (i * UINT_MAX) causes integer overflow due to 32-bit arithmetic.

This manifests when the input arg length >= 8 GiB results in looping for i >= 2.

Fix by casting i to dma_addr_t before multiplication.

Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping routine") Signed-off-by: Alex Mastro amastro@fb.com

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More color about how I discovered this in [1] for the commit at [2]:

[1] https://lore.kernel.org/all/aSZHO6otK0Heh+Qj@devgpu015.cco6.facebook.com [2] https://lore.kernel.org/all/20251120-dmabuf-vfio-v9-6-d7f71607f371@nvidia.co...

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drivers/dma-buf/dma-buf-mapping.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Jason Gunthorpe jgg@nvidia.com

AlexW, can you pick this up?

Thanks, Jason