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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-09 13:24:42 -0500 |
|---|---|---|
| committer | Trond Myklebust <trond.myklebust@hammerspace.com> | 2020-03-16 10:16:26 -0400 |
| commit | 5601cda82b0cc88c7d87b612c8b8b920de801be3 (patch) | |
| tree | 3f8b817a41ca72cdb6cc76b433393794d15c58d8 | |
| parent | f5fdf1243fb750598b46305dd03c553949cfa14f (diff) | |
| download | linux-5601cda82b0cc88c7d87b612c8b8b920de801be3.tar.bz2 | |
nfs: 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>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
| -rw-r--r-- | fs/nfs/dir.c | 2 | ||||
| -rw-r--r-- | fs/nfs/nfs4proc.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index b3a675da84a2..f14184d0ba82 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -141,7 +141,7 @@ struct nfs_cache_array { int size; int eof_index; u64 last_cookie; - struct nfs_cache_array_entry array[0]; + struct nfs_cache_array_entry array[]; }; typedef struct { diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 22dca497c5de..905c7d1bc277 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -5550,7 +5550,7 @@ unwind: struct nfs4_cached_acl { int cached; size_t len; - char data[0]; + char data[]; }; static void nfs4_set_cached_acl(struct inode *inode, struct nfs4_cached_acl *acl) |