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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-23 19:22:24 -0500
committerGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-18 15:44:56 -0500
commit5c91aa1df00ec4fa283c35e92736392df3137d81 (patch)
treeaf19bb8c2e6305d93893979de8d8e62a07c9b5d1 /include/linux/skbuff.h
parentfe946db6ca851a0cd8c2f9c9dd96ef74e051cf2f (diff)
skbuff.h: 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>
Diffstat (limited to 'include/linux/skbuff.h')
-rw-r--r--include/linux/skbuff.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 3a2ac7072dbb..3000c526f552 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4162,7 +4162,7 @@ struct skb_ext {
refcount_t refcnt;
u8 offset[SKB_EXT_NUM]; /* in chunks of 8 bytes */
u8 chunks; /* same */
- char data[0] __aligned(8);
+ char data[] __aligned(8);
};
struct skb_ext *__skb_ext_alloc(void);