soc: fsl: qe: Replace one-element array and use struct_size() helper

The current codebase makes use of one-element arrays in the following
form:

struct something {
    int length;
    u8 data[1];
};

struct something *instance;

instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
instance->length = size;
memcpy(instance->data, source, size);

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. So, replace
the one-element array with a flexible-array member.

Also, make use of the new struct_size() helper to properly calculate the
size of struct qe_firmware.

This issue was found with the help of Coccinelle and, audited and fixed
_manually_.

[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 <gustavoars@kernel.org>
Reviewed-by: Qiang Zhao <qiang.zhao@nxp.com>
Signed-off-by: Li Yang <leoyang.li@nxp.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/soc/fsl/qe/qe.h b/include/soc/fsl/qe/qe.h
index e282ac01ec08..3feddfec9f87 100644
--- a/include/soc/fsl/qe/qe.h
+++ b/include/soc/fsl/qe/qe.h
@@ -307,7 +307,7 @@ struct qe_firmware {
 		u8 revision;		/* The microcode version revision */
 		u8 padding;		/* Reserved, for alignment */
 		u8 reserved[4];		/* Reserved, for future expansion */
-	} __attribute__ ((packed)) microcode[1];
+	} __packed microcode[];
 	/* All microcode binaries should be located here */
 	/* CRC32 should be located here, after the microcode binaries */
 } __attribute__ ((packed));