* [PATCH][next] mei: hdcp: Replace one-element array with flexible-array member
@ 2020-07-22 18:15 Gustavo A. R. Silva
0 siblings, 0 replies; only message in thread
From: Gustavo A. R. Silva @ 2020-07-22 18:15 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman; +Cc: linux-kernel, Gustavo A. R. Silva
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, make use of the array_size() helper instead of the open-coded
version in memcpy(). These sorts of multiplication factors need to
be wrapped in array_size().
And while there, use the preferred form for passing a size of a struct.
The alternative form where struct name is spelled out hurts readability
and introduces an opportunity for a bug when the pointer variable type is
changed but the corresponding sizeof that is passed as argument is not.
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/79
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/misc/mei/hdcp/mei_hdcp.c | 2 +-
drivers/misc/mei/hdcp/mei_hdcp.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
index e6c3dc595617..d1d3e025ca0e 100644
--- a/drivers/misc/mei/hdcp/mei_hdcp.c
+++ b/drivers/misc/mei/hdcp/mei_hdcp.c
@@ -572,7 +572,7 @@ static int mei_hdcp_verify_mprime(struct device *dev,
HDCP_2_2_MPRIME_LEN);
drm_hdcp_cpu_to_be24(verify_mprime_in.seq_num_m, data->seq_num_m);
memcpy(verify_mprime_in.streams, data->streams,
- (data->k * sizeof(struct hdcp2_streamid_type)));
+ array_size(data->k, sizeof(*data->streams)));
verify_mprime_in.k = cpu_to_be16(data->k);
diff --git a/drivers/misc/mei/hdcp/mei_hdcp.h b/drivers/misc/mei/hdcp/mei_hdcp.h
index 18ffc773fa18..834757f5e072 100644
--- a/drivers/misc/mei/hdcp/mei_hdcp.h
+++ b/drivers/misc/mei/hdcp/mei_hdcp.h
@@ -358,7 +358,7 @@ struct wired_cmd_repeater_auth_stream_req_in {
u8 seq_num_m[HDCP_2_2_SEQ_NUM_LEN];
u8 m_prime[HDCP_2_2_MPRIME_LEN];
__be16 k;
- struct hdcp2_streamid_type streams[1];
+ struct hdcp2_streamid_type streams[];
} __packed;
struct wired_cmd_repeater_auth_stream_req_out {
--
2.27.0
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2020-07-22 18:10 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-22 18:15 [PATCH][next] mei: hdcp: Replace one-element array with flexible-array member Gustavo A. R. Silva
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).