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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 13:57:10 -0500
committerDavid Howells <dhowells@redhat.com>2020-06-02 17:22:31 +0100
commit2ce113fa525faf62fc308a10d1e5af07456b7460 (patch)
treed483a8b138ee383124e5f3f1aeade3d970ca23cf /include/keys
parent352780b61ebbd5fef845714c17246e1647c6904a (diff)
downloadlinux-2ce113fa525faf62fc308a10d1e5af07456b7460.tar.bz2
KEYS: 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: David Howells <dhowells@redhat.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Diffstat (limited to 'include/keys')
-rw-r--r--include/keys/user-type.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/keys/user-type.h b/include/keys/user-type.h
index be61fcddc02a..386c31432789 100644
--- a/include/keys/user-type.h
+++ b/include/keys/user-type.h
@@ -27,7 +27,7 @@
struct user_key_payload {
struct rcu_head rcu; /* RCU destructor */
unsigned short datalen; /* length of this data */
- char data[0] __aligned(__alignof__(u64)); /* actual data */
+ char data[] __aligned(__alignof__(u64)); /* actual data */
};
extern struct key_type key_type_user;