The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
drivers/video/fbdev/mmp/hw/mmp_ctrl.h | 2 +-
drivers/video/fbdev/ssd1307fb.c | 2 +-
include/video/mmp_disp.h | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/video/fbdev/mmp/hw/mmp_ctrl.h b/drivers/video/fbdev/mmp/hw/mmp_ctrl.h
index 335d4983dc52..167585a889d3 100644
--- a/drivers/video/fbdev/mmp/hw/mmp_ctrl.h
+++ b/drivers/video/fbdev/mmp/hw/mmp_ctrl.h
@@ -1406,7 +1406,7 @@ struct mmphw_ctrl {
/*pathes*/
int path_num;
- struct mmphw_path_plat path_plats[0];
+ struct mmphw_path_plat path_plats[];
};
static inline int overlay_is_vid(struct mmp_overlay *overlay)
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 142535267fec..fb2640fe575a 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -89,7 +89,7 @@ struct ssd1307fb_par {
struct ssd1307fb_array {
u8 type;
- u8 data[0];
+ u8 data[];
};
static const struct fb_fix_screeninfo ssd1307fb_fix = {
diff --git a/include/video/mmp_disp.h b/include/video/mmp_disp.h
index 1f9bc133e230..77252cb46361 100644
--- a/include/video/mmp_disp.h
+++ b/include/video/mmp_disp.h
@@ -231,7 +231,7 @@ struct mmp_path {
/* layers */
int overlay_num;
- struct mmp_overlay overlays[0];
+ struct mmp_overlay overlays[];
};
extern struct mmp_path *mmp_get_path(const char *name);
--
2.25.0
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