2021-03-25 03:36:59

by Gustavo A. R. Silva

Subject: [PATCH][next] SCSI: fusion: mpi_ioc.h: Replace one-element array with flexible-array member

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Also, this helps with the ongoing efforts to enable -Warray-bounds by
fixing the following warning:

drivers/message/fusion/mptbase.c: In function ‘mptbase_reply’:
drivers/message/fusion/mptbase.c:7747:62: warning: array subscript 1 is above array bounds of ‘U32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds]
7747 | ioc->events[idx].data[ii] = le32_to_cpu(pEventReply->Data[ii]);
./include/uapi/linux/byteorder/little_endian.h:34:51: note: in definition of macro ‘__le32_to_cpu’
34 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
| ^
drivers/message/fusion/mptbase.c:7747:33: note: in expansion of macro ‘le32_to_cpu’
7747 | ioc->events[idx].data[ii] = le32_to_cpu(pEventReply->Data[ii]);
|

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/message/fusion/lsi/mpi_ioc.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/message/fusion/lsi/mpi_ioc.h b/drivers/message/fusion/lsi/mpi_ioc.h
index c249f2994fc1..1534460fd5b1 100644
--- a/drivers/message/fusion/lsi/mpi_ioc.h
+++ b/drivers/message/fusion/lsi/mpi_ioc.h
@@ -448,7 +448,7 @@ typedef struct _MSG_EVENT_NOTIFY_REPLY
U32 IOCLogInfo; /* 10h */
U32 Event; /* 14h */
U32 EventContext; /* 18h */
- U32 Data[1]; /* 1Ch */
+ U32 Data[]; /* 1Ch */
} MSG_EVENT_NOTIFY_REPLY, MPI_POINTER PTR_MSG_EVENT_NOTIFY_REPLY,
EventNotificationReply_t, MPI_POINTER pEventNotificationReply_t;

--
2.27.0

2021-04-06 13:15:59

by Martin K. Petersen

Subject: Re: [PATCH][next] SCSI: fusion: mpi_ioc.h: Replace one-element array with flexible-array member

On Wed, 24 Mar 2021 18:00:36 -0500, Gustavo A. R. Silva wrote:

> There is a regular need in the kernel to provide a way to declare having
> a dynamically sized set of trailing elements in a structure. Kernel code
> should always use “flexible array members”[1] for these cases. The older
> style of one-element or zero-length arrays should no longer be used[2].
>
> Also, this helps with the ongoing efforts to enable -Warray-bounds by
> fixing the following warning:
>
> [...]

Applied to 5.13/scsi-queue, thanks!

[1/1] SCSI: fusion: mpi_ioc.h: Replace one-element array with flexible-array member
https://git.kernel.org/mkp/scsi/c/ed46ccc7fe76

--
Martin K. Petersen Oracle Linux Engineering