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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 12:29:54 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2020-05-09 22:15:41 -0700
commitd34fced41e172fae2df7819b1d5a398c62067599 (patch)
tree730b44311b1d63298e0c7075a9ef10f2e288058f
parent9747070c11d6ae021ed7a8e96e2950ed46cd53a9 (diff)
downloadlinux-sh-d34fced41e172fae2df7819b1d5a398c62067599.tar.gz
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>
-rw-r--r--drivers/input/keyboard/applespi.c2
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[];
};
/**