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From:   Stephen Kitt <steve@sk2.org>
To:     Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
        Kai Vehmanen <kai.vehmanen@linux.intel.com>,
        Daniel Baluta <daniel.baluta@nxp.com>
Cc:     alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
        sound-open-firmware@alsa-project.org, Stephen Kitt <steve@sk2.org>,
        "Gustavo A . R . Silva" <gustavoars@kernel.org>
Subject: [PATCH] ASoC: SOF: Replace zero-length array with flexible-array member
Date:   Thu, 17 Feb 2022 14:27:55 +0100
Message-Id: <20220217132755.1786130-1-steve@sk2.org>
MIME-Version: 1.0
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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].

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

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

Link: https://github.com/KSPP/linux/issues/78
Link: https://github.com/KSPP/linux/issues/180
Suggested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Stephen Kitt <steve@sk2.org>
---
 include/sound/sof/topology.h | 2 +-
 sound/soc/sof/topology.c     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/sound/sof/topology.h b/include/sound/sof/topology.h
index d12736e14b69..adee6afd1490 100644
--- a/include/sound/sof/topology.h
+++ b/include/sound/sof/topology.h
@@ -237,7 +237,7 @@ struct sof_ipc_comp_process {
 	/* reserved for future use */
 	uint32_t reserved[7];
 
-	uint8_t data[0];
+	uint8_t data[];
 } __packed;
 
 /* frees components, buffers and pipelines
diff --git a/sound/soc/sof/topology.c b/sound/soc/sof/topology.c
index e72dcae5e7ee..1d119d1dd69d 100644
--- a/sound/soc/sof/topology.c
+++ b/sound/soc/sof/topology.c
@@ -2164,7 +2164,7 @@ static int sof_process_load(struct snd_soc_component *scomp, int index,
 	 */
 	if (ipc_data_size) {
 		for (i = 0; i < widget->num_kcontrols; i++) {
-			memcpy(&process->data + offset,
+			memcpy(&process->data[offset],
 			       wdata[i].pdata->data,
 			       wdata[i].pdata->size);
 			offset += wdata[i].pdata->size;

base-commit: f71077a4d84bbe8c7b91b7db7c4ef815755ac5e3
-- 
2.27.0