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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-09 13:24:42 -0500
committerTrond Myklebust <trond.myklebust@hammerspace.com>2020-03-16 10:16:26 -0400
commit5601cda82b0cc88c7d87b612c8b8b920de801be3 (patch)
tree3f8b817a41ca72cdb6cc76b433393794d15c58d8
parentf5fdf1243fb750598b46305dd03c553949cfa14f (diff)
downloadlinux-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.c2
-rw-r--r--fs/nfs/nfs4proc.c2
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)