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 --- include/scsi/scsi_device.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/scsi/scsi_device.h') diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index f146a4557787..579e24c92f2f 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -230,7 +230,7 @@ struct scsi_device { struct mutex state_mutex; enum scsi_device_state sdev_state; struct task_struct *quiesced_by; - unsigned long sdev_data[0]; + unsigned long sdev_data[]; } __attribute__((aligned(sizeof(unsigned long)))); #define to_scsi_device(d) \ @@ -314,7 +314,7 @@ struct scsi_target { char scsi_level; enum scsi_target_state state; void *hostdata; /* available to low-level driver */ - unsigned long starget_data[0]; /* for the transport */ + unsigned long starget_data[]; /* for the transport */ /* starget_data must be the last element!!!! */ } __attribute__((aligned(sizeof(unsigned long)))); -- cgit v1.2.3