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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 22:02:23 +0300
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2020-05-27 17:10:12 +0300
commit1ad8dd939a9826ff6f8c69ac13e4e1dbba076703 (patch)
tree69a43dada6b0e52742c490a112a9f34b63e674ad /include/linux/nfs_xdr.h
parent1c709b766e73e54d64b1dde1b7cfbcf25bcb15b9 (diff)
downloadlinux-1ad8dd939a9826ff6f8c69ac13e4e1dbba076703.tar.xz
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>
Diffstat (limited to 'include/linux/nfs_xdr.h')
-rw-r--r--include/linux/nfs_xdr.h2
1 files changed, 1 insertions, 1 deletions
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 {