From 5febf6d6ae4d488a5dc388c46d96c17f9556238f Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 10:14:06 -0600 Subject: scsi: 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") Link: https://lore.kernel.org/r/20200224161406.GA21454@embeddedor Reviewed-by: Lee Duncan Reviewed-by: Satish Kharat Signed-off-by: Gustavo A. R. Silva Signed-off-by: Martin K. Petersen --- drivers/scsi/isci/sas.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/scsi/isci') diff --git a/drivers/scsi/isci/sas.h b/drivers/scsi/isci/sas.h index dc26b4aea99e..15d8f3631ab7 100644 --- a/drivers/scsi/isci/sas.h +++ b/drivers/scsi/isci/sas.h @@ -201,7 +201,7 @@ struct smp_req { u8 func; /* byte 1 */ u8 alloc_resp_len; /* byte 2 */ u8 req_len; /* byte 3 */ - u8 req_data[0]; + u8 req_data[]; } __packed; /* -- cgit