2023-01-05 19:56:58

by Kees Cook

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

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 <[email protected]>
Cc: "Gustavo A. R. Silva" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
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

2023-01-06 16:11:43

by Gustavo A. R. Silva

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

On Thu, Jan 05, 2023 at 11:20:38AM -0800, Kees Cook wrote:
> 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 <[email protected]>
> Cc: "Gustavo A. R. Silva" <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Reviewed-by: Gustavo A. R. Silva <[email protected]>

Thanks!
--
Gustavo

> ---
> 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
>

2023-01-09 08:33:31

by Helge Deller

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

On 1/5/23 20:20, Kees Cook wrote:
> 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 <[email protected]>
> Cc: "Gustavo A. R. Silva" <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

applied to the fbdev git tree.

Thanks!
Helge

> ---
> 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 */