[PATCH] drm/panthor: fix firmware control interface bounds checks

[Osama Abdelkader]

panthor_init_cs_iface() and panthor_init_csg_iface() validate firmware
control interface offsets with 32-bit arithmetic and the size of the host
wrapper structures. The offsets are derived from firmware-provided strides,
so the arithmetic can wrap before the bounds check, and the host wrapper
size is not the size of the firmware control interface being mapped.

Use 64-bit arithmetic for the computed offsets and validate against the
actual firmware control interface structure sizes with subtraction-based
bounds checks. Also validate that the shared section is large enough for
the global control interface before using it.

Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Osama Abdelkader <osama.abdelkader@xxxxxxxxx>
---
 drivers/gpu/drm/panthor/panthor_fw.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index eee2bc7e8541..e2fcbd639c3c 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -897,15 +897,16 @@ static int panthor_init_cs_iface(struct panthor_device *ptdev,
 	struct panthor_fw_csg_iface *csg_iface = panthor_fw_get_csg_iface(ptdev, csg_idx);
 	struct panthor_fw_cs_iface *cs_iface = &ptdev->fw->iface.streams[csg_idx][cs_idx];
 	u64 shared_section_sz = panthor_kernel_bo_size(ptdev->fw->shared_section->mem);
-	u32 iface_offset = CSF_GROUP_CONTROL_OFFSET +
-			   (csg_idx * glb_iface->control->group_stride) +
+	u64 iface_offset = CSF_GROUP_CONTROL_OFFSET +
+			   ((u64)csg_idx * glb_iface->control->group_stride) +
 			   CSF_STREAM_CONTROL_OFFSET +
-			   (cs_idx * csg_iface->control->stream_stride);
+			   ((u64)cs_idx * csg_iface->control->stream_stride);
 	struct panthor_fw_cs_iface *first_cs_iface =
 		panthor_fw_get_cs_iface(ptdev, 0, 0);
 
-	if (iface_offset + sizeof(*cs_iface) >= shared_section_sz)
+	if (iface_offset > shared_section_sz ||
+	    sizeof(*cs_iface->control) > shared_section_sz - iface_offset)
 		return -EINVAL;
 
 	spin_lock_init(&cs_iface->lock);
 	cs_iface->control = ptdev->fw->shared_section->mem->kmap + iface_offset;
@@ -955,11 +956,13 @@ static int panthor_init_csg_iface(struct panthor_device *ptdev,
 	struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
 	struct panthor_fw_csg_iface *csg_iface = &ptdev->fw->iface.groups[csg_idx];
 	u64 shared_section_sz = panthor_kernel_bo_size(ptdev->fw->shared_section->mem);
-	u32 iface_offset = CSF_GROUP_CONTROL_OFFSET + (csg_idx * glb_iface->control->group_stride);
+	u64 iface_offset = CSF_GROUP_CONTROL_OFFSET +
+			   ((u64)csg_idx * glb_iface->control->group_stride);
 	unsigned int i;
 
-	if (iface_offset + sizeof(*csg_iface) >= shared_section_sz)
+	if (iface_offset > shared_section_sz ||
+	    sizeof(*csg_iface->control) > shared_section_sz - iface_offset)
 		return -EINVAL;
 
 	spin_lock_init(&csg_iface->lock);
 	csg_iface->control = ptdev->fw->shared_section->mem->kmap + iface_offset;
@@ -1011,12 +1014,16 @@ static u32 panthor_get_instr_features(struct panthor_device *ptdev)
 static int panthor_fw_init_ifaces(struct panthor_device *ptdev)
 {
 	struct panthor_fw_global_iface *glb_iface = &ptdev->fw->iface.global;
+	u64 shared_section_sz = panthor_kernel_bo_size(ptdev->fw->shared_section->mem);
 	unsigned int i;
 
 	if (!ptdev->fw->shared_section->mem->kmap)
 		return -EINVAL;
 
+	if (sizeof(*glb_iface->control) > shared_section_sz)
+		return -EINVAL;
+
 	spin_lock_init(&glb_iface->lock);
 	glb_iface->control = ptdev->fw->shared_section->mem->kmap;
 
 	if (!glb_iface->control->version) {
-- 
2.43.0