From: Gustavo A. R. Silva Date: Thu, 19 Mar 2020 21:31:08 +0000 (-0500) Subject: HID: intel-ish-hid: ishtp-dev.h: Replace zero-length array with flexible-array member X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=71559219ce36d5861ecc1d31697687c08819b6e5;p=openwrt%2Fstaging%2Fblogic.git HID: intel-ish-hid: ishtp-dev.h: Replace zero-length array with flexible-array member 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 Signed-off-by: Jiri Kosina --- diff --git a/drivers/hid/intel-ish-hid/ishtp/ishtp-dev.h b/drivers/hid/intel-ish-hid/ishtp/ishtp-dev.h index 39e0e6c73adf..1cc6364aa957 100644 --- a/drivers/hid/intel-ish-hid/ishtp/ishtp-dev.h +++ b/drivers/hid/intel-ish-hid/ishtp/ishtp-dev.h @@ -214,7 +214,7 @@ struct ishtp_device { const struct ishtp_hw_ops *ops; size_t mtu; uint32_t ishtp_msg_hdr; - char hw[0] __aligned(sizeof(void *)); + char hw[] __aligned(sizeof(void *)); }; static inline unsigned long ishtp_secs_to_jiffies(unsigned long sec)