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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-23 19:51:46 -0500
committerGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-18 15:44:56 -0500
commitd6cdad870358128c1e753e6258e295ab8a5a2429 (patch)
treeeb21c55e5066118b84fa19361a9e9bd3d62a46c6
parent06ccf63da5d8e90e4dff8b741972a9b279b5bf4c (diff)
uapi: linux: dlm_device.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 <gustavo@embeddedor.com>
-rw-r--r--include/uapi/linux/dlm_device.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/uapi/linux/dlm_device.h b/include/uapi/linux/dlm_device.h
index f880d2831160..e83954c69fff 100644
--- a/include/uapi/linux/dlm_device.h
+++ b/include/uapi/linux/dlm_device.h
@@ -45,13 +45,13 @@ struct dlm_lock_params {
void __user *bastaddr;
struct dlm_lksb __user *lksb;
char lvb[DLM_USER_LVB_LEN];
- char name[0];
+ char name[];
};
struct dlm_lspace_params {
__u32 flags;
__u32 minor;
- char name[0];
+ char name[];
};
struct dlm_purge_params {