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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-24 03:08:58 +0300
committerGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-18 23:44:55 +0300
commit70f1451ec98ee43d2c66d2caa5ae6935ee97f90a (patch)
tree5b05e9e1a2809507719083bc4bccba37d3d0ab48
parent1223f3db71ba7bbcf2e77c7a5d4f440c2a2fa9c3 (diff)
downloadlinux-70f1451ec98ee43d2c66d2caa5ae6935ee97f90a.tar.xz
posix_acl.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/linux/posix_acl.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 540595a321a7..90797f1b421d 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -28,7 +28,7 @@ struct posix_acl {
refcount_t a_refcount;
struct rcu_head a_rcu;
unsigned int a_count;
- struct posix_acl_entry a_entries[0];
+ struct posix_acl_entry a_entries[];
};
#define FOREACH_ACL_ENTRY(pa, acl, pe) \