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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-02 06:00:48 -0600
committerDavid S. Miller <davem@davemloft.net>2020-03-02 11:16:27 -0800
commit2e83abdcb30e3881e9569fd8f4a600beef6cfadc (patch)
tree5d0bb3443b5dc1c7b9df393fd4d94bb11b203b4a /include
parentbb4cf02d4c74f0db60f58c406ddfdfed16d14f84 (diff)
net: mip6: 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>
Diffstat (limited to 'include')
-rw-r--r--include/net/mip6.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/mip6.h b/include/net/mip6.h
index f1c28971c362..67cd7e50804c 100644
--- a/include/net/mip6.h
+++ b/include/net/mip6.h
@@ -25,7 +25,7 @@ struct ip6_mh {
__u8 ip6mh_reserved;
__u16 ip6mh_cksum;
/* Followed by type specific messages */
- __u8 data[0];
+ __u8 data[];
} __packed;
#define IP6_MH_TYPE_BRR 0 /* Binding Refresh Request */