ASoC: wm0010: Replace zero-length array with flexible-array member
authorGustavo A. R. Silva <gustavo@embeddedor.com>
Tue, 11 Feb 2020 20:05:49 +0000 (14:05 -0600)
committerMark Brown <broonie@kernel.org>
Wed, 12 Feb 2020 19:13:40 +0000 (19:13 +0000)
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
inadvertenly introduced[3] to the codebase from now on.

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@embeddedor.com>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20200211200549.GA12072@embeddedor
Signed-off-by: Mark Brown <broonie@kernel.org>
sound/soc/codecs/wm0010.c

index 727d670..fbcee21 100644 (file)
@@ -43,7 +43,7 @@ struct dfw_binrec {
        u8 command;
        u32 length:24;
        u32 address;
-       uint8_t data[0];
+       uint8_t data[];
 } __packed;
 
 struct dfw_inforec {