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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-02 06:07:42 -0600
committerDavid S. Miller <davem@davemloft.net>2020-03-02 11:16:28 -0800
commit48b77df665e0a268b61a795208e647b6b7bb7e00 (patch)
treef429ccb5cb0d1496f79ded87fad1aeabf7d1fc0e
parent6e68f499e93429e521af40cb25129f27c6c80a10 (diff)
net: inet_sock: 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: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/inet_sock.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 34c4436fd18f..a7ce00af6c44 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -52,7 +52,7 @@ struct ip_options {
unsigned char router_alert;
unsigned char cipso;
unsigned char __pad2;
- unsigned char __data[0];
+ unsigned char __data[];
};
struct ip_options_rcu {