diff options
| author | Gustavo A. R. Silva | 2020-05-07 14:02:23 -0500 |
|---|---|---|
| committer | Anna Schumaker | 2020-05-27 10:10:12 -0400 |
| commit | 1ad8dd939a9826ff6f8c69ac13e4e1dbba076703 (patch) | |
| tree | 69a43dada6b0e52742c490a112a9f34b63e674ad | |
| parent | 1c709b766e73e54d64b1dde1b7cfbcf25bcb15b9 (diff) | |
NFS: Replace zero-length array with flexible-array
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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
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 <gustavoars@kernel.org>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
| -rw-r--r-- | include/linux/nfs4.h | 2 | ||||
| -rw-r--r-- | include/linux/nfs_xdr.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h index 4a51db7363a5..4dba3c948932 100644 --- a/include/linux/nfs4.h +++ b/include/linux/nfs4.h @@ -38,7 +38,7 @@ struct nfs4_ace { struct nfs4_acl { uint32_t naces; - struct nfs4_ace aces[0]; + struct nfs4_ace aces[]; }; #define NFS4_MAXLABELLEN 2048 diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h index e5f3e7d8d3d5..5fd0a9ef425f 100644 --- a/include/linux/nfs_xdr.h +++ b/include/linux/nfs_xdr.h @@ -1227,7 +1227,7 @@ struct nfs4_secinfo4 { struct nfs4_secinfo_flavors { unsigned int num_flavors; - struct nfs4_secinfo4 flavors[0]; + struct nfs4_secinfo4 flavors[]; }; struct nfs4_secinfo_arg { |