[PATCH 7.1 026/228] drm/panthor: skip zero-sized firmware sections

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Osama Abdelkader <[email protected]>

commit 2b8f13d3c7e26c46c20d9e367904cf01729c88e6 upstream.

panthor_fw_load_section_entry() skips BO creation when the firmware section
VA range is empty. If such a section is added to the firmware section list,
section->mem is left as NULL.

Later reload and unplug paths iterate over all firmware sections and
dereference section->mem, which can lead to a NULL pointer dereference.

Zero-sized firmware sections are valid, so accept them as no-op entries but
skip adding them to the section list.

Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
Cc: [email protected]
Signed-off-by: Osama Abdelkader <[email protected]>
Reviewed-by: Liviu Dudau <[email protected]>
Reviewed-by: Steven Price <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Steven Price <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/panthor/panthor_fw.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -600,6 +600,9 @@ static int panthor_fw_load_section_entry
 		return -EINVAL;
 	}
 
+	if (!section_size)
+		return 0;
+
 	name_len = iter->size - iter->offset;
 
 	section = drmm_kzalloc(&ptdev->base, sizeof(*section), GFP_KERNEL);