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| author |   Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 12:29:54 -0700 |
|---|---|---|
| committer |   Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2020-05-09 22:15:41 -0700 |
| commit | d34fced41e172fae2df7819b1d5a398c62067599 (patch) | |
| tree | 730b44311b1d63298e0c7075a9ef10f2e288058f /drivers/input | |
| parent | Input: axp20x-pek - always register interrupt handlers (diff) | |
| download | linux-dev-d34fced41e172fae2df7819b1d5a398c62067599.tar.xz linux-dev-d34fced41e172fae2df7819b1d5a398c62067599.zip | |
Input: applespi - replace zero-length array with flexible-array
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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
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 <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200507185347.GA14499@embeddedor
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'drivers/input')
| -rw-r--r-- | drivers/input/keyboard/applespi.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/input/keyboard/applespi.c b/drivers/input/keyboard/applespi.c index d38398526965..14362ebab9a9 100644 --- a/drivers/input/keyboard/applespi.c +++ b/drivers/input/keyboard/applespi.c @@ -186,7 +186,7 @@ struct touchpad_protocol { u8 number_of_fingers; u8 clicked2; u8 unknown3[16]; - struct tp_finger fingers[0]; + struct tp_finger fingers[]; }; /** |