Messages in this thread Patch in this message |  | | From | Sebastian Alba Vives <> | | Subject | [PATCH v3 2/3] fpga: dfl-afu: validate DMA mapping length in afu_dma_map_region() | | Date | Tue, 7 Apr 2026 08:17:35 -0600 |
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afu_ioctl_dma_map() accepts a 64-bit length from userspace via DFL_FPGA_PORT_DMA_MAP ioctl without an upper bound check. The value is passed to afu_dma_pin_pages() where npages is derived as length >> PAGE_SHIFT and passed to pin_user_pages_fast() which takes int nr_pages, causing implicit truncation if length is very large.
Validate map.length at the ioctl entry point before calling afu_dma_map_region(), rejecting values whose page count exceeds INT_MAX.
Signed-off-by: Sebastian Alba Vives <sebasjosue84@gmail.com> --- Changes in v3: - Move the upper-bound check on map.length to afu_ioctl_dma_map() at the ioctl entry point, before crossing the userspace/kernel boundary, instead of deep in afu_dma_pin_pages(). Revert changes to dfl-afu-dma-region.c from v1/v2. Suggested by Greg Kroah-Hartman. Changes in v2: - Added cap at INT_MAX in afu_dma_pin_pages() (superseded by v3). --- drivers/fpga/dfl-afu-main.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c index 3bf8e73..097a97e 100644 --- a/drivers/fpga/dfl-afu-main.c +++ b/drivers/fpga/dfl-afu-main.c @@ -723,6 +723,9 @@ afu_ioctl_dma_map(struct dfl_feature_dev_data *fdata, void __user *arg) if (map.argsz < minsz || map.flags) return -EINVAL; + if (map.length >> PAGE_SHIFT > (u64)INT_MAX) + return -EINVAL; + ret = afu_dma_map_region(fdata, map.user_addr, map.length, &map.iova); if (ret) return ret; -- 2.43.0
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