[PATCH] fbdev: Replace 0-length array with flexible array

Kees Cook
2023-01-05T19:27:02Z

Zero-length arrays are deprecated[1]. Replace struct aperture's "ranges"
0-length array with a flexible array. (How is the size of this array
verified?) Detected with GCC 13, using -fstrict-flex-arrays=3:

samples/vfio-mdev/mdpy-fb.c: In function 'mdpy_fb_probe':
samples/vfio-mdev/mdpy-fb.c:169:32: warning: array subscript 0 is outside array bounds of 'struct aperture[0]' [-Warray-bounds=]
169 | info->apertures->ranges[0].base = info->fix.smem_start;
| ~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from samples/vfio-mdev/mdpy-fb.c:21:
include/linux/fb.h:510:19: note: while referencing 'ranges'
510 | } ranges[0];
| ^~~~~~

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays

Cc: Helge Deller <deller@gmx.de>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/linux/fb.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fb.h b/include/linux/fb.h
index 96b96323e9cb..bf59d6a3590f 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -507,7 +507,7 @@ struct fb_info {
struct aperture {
resource_size_t base;
resource_size_t size;
- } ranges[0];
+ } ranges[];
} *apertures;

bool skip_vt_switch; /* no VT switch on suspend/resume required */
--
2.34.1