[PATCH] fpga: Add __counted_by_ptr annotation to fpga_image_info

[Bill Wendling <morbo@google.com>]

The 'const char *buf' pointer in 'struct fpga_image_info' is used to hold
the FPGA image data, and its element count is stored in 'size_t count'.
To strengthen runtime boundary checks via KASAN and
'__builtin_dynamic_object_size', annotate the 'buf' field with the
'__counted_by_ptr' attribute, pointing to 'count'.

All allocation and assignment paths of 'struct fpga_image_info' have been
verified to ensure that 'count' is initialized before or alongside 'buf',
and 'buf' is never accessed before 'count' is set.

Cc: codemender-patching+linux@google.com
Assisted-by: LLM
Signed-off-by: Bill Wendling <morbo@google.com>
---
 include/linux/fpga/fpga-mgr.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
index 0d4fe068f3d8..fb9b0978bd34 100644
--- a/include/linux/fpga/fpga-mgr.h
+++ b/include/linux/fpga/fpga-mgr.h
@@ -103,7 +103,7 @@ struct fpga_image_info {
 	u32 config_complete_timeout_us;
 	char *firmware_name;
 	struct sg_table *sgt;
-	const char *buf;
+	const char *buf __counted_by_ptr(count);
 	size_t count;
 	size_t header_size;
 	size_t data_size;
-- 
2.56.0.rc1.315.gc6ed9934b7-goog