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")
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| @@ -73,7 +73,7 @@ struct bpf_insn { · 72 unmodified lines | ||
| 73 | 73 | /* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */ |
| 74 | 74 | struct bpf_lpm_trie_key { |
| 75 | 75 | __u32 prefixlen; /* up to 32 for AF_INET, 128 for AF_INET6 */ |
| 76 | − __u8 data[0]; /* Arbitrary size */ | |
| 76 | + __u8 data[]; /* Arbitrary size */ | |
| 77 | 77 | }; |
| 78 | 78 | |
| 79 | 79 | struct bpf_cgroup_storage_key { |