From 23640d641255be9d709c2eddfb0b37ca3c4aeabe Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Date: Mon, 2 Mar 2020 06:28:26 -0600 Subject: tehuti: 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> --- drivers/net/ethernet/tehuti/tehuti.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/net/ethernet/tehuti') diff --git a/drivers/net/ethernet/tehuti/tehuti.h b/drivers/net/ethernet/tehuti/tehuti.h index 5fc03c8eba0c..909e7296cecf 100644 --- a/drivers/net/ethernet/tehuti/tehuti.h +++ b/drivers/net/ethernet/tehuti/tehuti.h @@ -330,7 +330,7 @@ struct txd_desc { u16 length; u32 va_lo; u32 va_hi; - struct pbl pbl[0]; /* Fragments */ + struct pbl pbl[]; /* Fragments */ } __packed; /* Register region size */ -- cgit v1.2.3