[PATCH v8 0/3] fpga: bounds checks and input validation fixes

[PATCH v8 0/3] fpga: bounds checks and input validation fixes

[Sebastian Alba Vives]

This series adds three defensive fixes to FPGA drivers:

Patch 1/3 fixes dfh_get_param_size() in the DFL driver where the loop
bounds check is evaluated before incrementing size, potentially returning
an inflated size that exceeds the feature region boundary.

Patch 2/3 validates the DMA mapping length in afu_ioctl_dma_map() at the
ioctl entry point before passing it down the call chain, preventing
implicit integer truncation in pin_user_pages_fast().

Patch 3/3 fixes mpf_ops_parse_header() in the Microchip SPI FPGA manager
where a zero header_size from the bitstream causes a one-byte read before
the buffer start.

Sebastian Alba Vives (3):
  fpga: dfl: add bounds check in dfh_get_param_size()
  fpga: dfl-afu: validate DMA mapping length in afu_dma_map_region()
  fpga: microchip-spi: fix zero header_size OOB read in
    mpf_ops_parse_header()

 drivers/fpga/dfl-afu-main.c  | 3 +++
 drivers/fpga/dfl.c           | 2 ++
 drivers/fpga/microchip-spi.c | 3 +++
 3 files changed, 8 insertions(+)

-- 
2.43.0

[PATCH v8 1/3] fpga: dfl: add bounds check in dfh_get_param_size()

[Sebastian Alba Vives]

dfh_get_param_size() can return a parameter size larger than the feature
region because the loop bounds check is evaluated before incrementing
size. If the EOP (End of Parameters) bit is set in the same iteration,
the inflated size is returned without re-validation against max.

This can cause create_feature_instance() to call memcpy_fromio() with a
size exceeding the ioremap'd region when a malicious FPGA device provides
crafted DFHv1 parameter headers.

Add a bounds check after the size increment to ensure the accumulated
size never exceeds the feature boundary.

Fixes: 4747ab89b4a6 ("fpga: dfl: add basic support for DFHv1")
Cc: stable@vger.kernel.org
Signed-off-by: Sebastian Alba Vives <sebasjosue84@gmail.com>
---
Changes in v8:
  - Add Cc: stable tag.
    Reported by Greg Kroah-Hartman.
Changes in v7:
  - Correct the Fixes: tag commit hash (checkpatch).
    Reported by Xu Yilun.
Changes in v6:
  - Rebase onto linux-next. Add cover letter.
    Suggested by Xu Yilun.
Changes in v5:
  - Add blank line after the new bounds check.
    Suggested by Xu Yilun.
---
 drivers/fpga/dfl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 4087a36a0..4c63c7c85 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -1132,6 +1132,8 @@ static int dfh_get_param_size(void __iomem *dfh_base, resource_size_t max)
 			return -EINVAL;
 
 		size += next * sizeof(u64);
+		if (size > max)
+			return -EINVAL;
 
 		if (FIELD_GET(DFHv1_PARAM_HDR_NEXT_EOP, v))
 			return size;
-- 
2.43.0

[PATCH v8 2/3] fpga: dfl-afu: validate DMA mapping length in afu_dma_map_region()

[Sebastian Alba Vives]

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.

Fixes: fa8dda1edef9 ("fpga: dfl: afu: add DFL_FPGA_PORT_DMA_MAP/UNMAP ioctls support")
Cc: stable@vger.kernel.org
Signed-off-by: Sebastian Alba Vives <sebasjosue84@gmail.com>
---
Changes in v8:
  - Add Fixes: and Cc: stable tags.
    Reported by Greg Kroah-Hartman.
Changes in v6:
  - Rebase onto linux-next. Add cover letter.
    Suggested by Xu Yilun.
Changes in v3:
  - Move validation to afu_ioctl_dma_map() at the ioctl entry point.
    Suggested by Greg Kroah-Hartman.
---
 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 3bf8e7338..097a97eee 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

[PATCH v8 3/3] fpga: microchip-spi: fix zero header_size OOB read in mpf_ops_parse_header()

[Sebastian Alba Vives]

mpf_ops_parse_header() reads header_size from the bitstream at
MPF_HEADER_SIZE_OFFSET (24). When header_size is zero, the expression
*(buf + header_size - 1) reads one byte before the buffer start.

Since initial_header_size is set to 71 in mpf_ops, the fpga-mgr core
guarantees the buffer is large enough to reach MPF_HEADER_SIZE_OFFSET.
The only real gap is the zero header_size case, which cannot be
resolved by providing a larger buffer, so return -EINVAL.

Fixes: 5f8d4a900830 ("fpga: microchip-spi: add Microchip MPF FPGA manager")
Cc: stable@vger.kernel.org
Signed-off-by: Sebastian Alba Vives <sebasjosue84@gmail.com>
---
Changes in v8:
  - No changes.
Changes in v7:
  - Correct the Fixes: tag commit hash and wrap commit message
    at 75 columns (checkpatch).
Changes in v6:
  - Rebase onto linux-next. Add cover letter.
    Suggested by Xu Yilun.
Changes in v5:
  - Drop redundant count check since initial_header_size = 71 already
    guarantees the buffer covers MPF_HEADER_SIZE_OFFSET.
    Suggested by Xu Yilun.
---
 drivers/fpga/microchip-spi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/fpga/microchip-spi.c b/drivers/fpga/microchip-spi.c
index 6134cea86..cc8f6d7bb 100644
--- a/drivers/fpga/microchip-spi.c
+++ b/drivers/fpga/microchip-spi.c
@@ -116,6 +116,9 @@ static int mpf_ops_parse_header(struct fpga_manager *mgr,
 	}
 
 	header_size = *(buf + MPF_HEADER_SIZE_OFFSET);
+	if (!header_size)
+		return -EINVAL;
+
 	if (header_size > count) {
 		info->header_size = header_size;
 		return -EAGAIN;
-- 
2.43.0

Re: [PATCH v8 0/3] fpga: bounds checks and input validation fixes

[Xu Yilun]

On Mon, May 18, 2026 at 01:07:39PM -0600, Sebastian Alba Vives wrote:
> This series adds three defensive fixes to FPGA drivers:
> 
> Patch 1/3 fixes dfh_get_param_size() in the DFL driver where the loop
> bounds check is evaluated before incrementing size, potentially returning
> an inflated size that exceeds the feature region boundary.
> 
> Patch 2/3 validates the DMA mapping length in afu_ioctl_dma_map() at the
> ioctl entry point before passing it down the call chain, preventing
> implicit integer truncation in pin_user_pages_fast().
> 
> Patch 3/3 fixes mpf_ops_parse_header() in the Microchip SPI FPGA manager
> where a zero header_size from the bitstream causes a one-byte read before
> the buffer start.
> 
> Sebastian Alba Vives (3):
>   fpga: dfl: add bounds check in dfh_get_param_size()
>   fpga: dfl-afu: validate DMA mapping length in afu_dma_map_region()
>   fpga: microchip-spi: fix zero header_size OOB read in
>     mpf_ops_parse_header()
> 
>  drivers/fpga/dfl-afu-main.c  | 3 +++
>  drivers/fpga/dfl.c           | 2 ++
>  drivers/fpga/microchip-spi.c | 3 +++
>  3 files changed, 8 insertions(+)

Reviewed-by: Xu Yilun <yilun.xu@intel.com>

Applied to for-next