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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-24 03:08:58 +0300 |
|---|---|---|
| committer | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-04-18 23:44:55 +0300 |
| commit | 70f1451ec98ee43d2c66d2caa5ae6935ee97f90a (patch) | |
| tree | 5b05e9e1a2809507719083bc4bccba37d3d0ab48 | |
| parent | 1223f3db71ba7bbcf2e77c7a5d4f440c2a2fa9c3 (diff) | |
| download | linux-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.h | 2 |
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) \ |