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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| @@ -29,7 +29,7 @@ struct pubkey_hdr { · 28 unmodified lines | ||
| 29 | 29 | uint32_t timestamp; /* key made, always 0 for now */ |
| 30 | 30 | uint8_t algo; |
| 31 | 31 | uint8_t nmpi; |
| 32 | − char mpi[0]; | |
| 32 | + char mpi[]; | |
| 33 | 33 | } __packed; |
| 34 | 34 | |
| 35 | 35 | struct signature_hdr { |
| @@ -39,7 +39,7 @@ struct signature_hdr { · 3 unmodified lines | ||
| 39 | 39 | uint8_t hash; |
| 40 | 40 | uint8_t keyid[8]; |
| 41 | 41 | uint8_t nmpi; |
| 42 | − char mpi[0]; | |
| 42 | + char mpi[]; | |
| 43 | 43 | } __packed; |
| 44 | 44 | |
| 45 | 45 | #if defined(CONFIG_SIGNATURE) || defined(CONFIG_SIGNATURE_MODULE) |