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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
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")
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
sound/soc/intel/atom/sst-atom-controls.h | 2 +-
sound/soc/intel/skylake/skl-i2s.h | 2 +-
sound/soc/intel/skylake/skl-topology.h | 4 ++--
sound/soc/intel/skylake/skl.h | 2 +-
4 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/sound/soc/intel/atom/sst-atom-controls.h b/sound/soc/intel/atom/sst-atom-controls.h
index 5356e954a732..620b48d2a064 100644
--- a/sound/soc/intel/atom/sst-atom-controls.h
+++ b/sound/soc/intel/atom/sst-atom-controls.h
@@ -410,7 +410,7 @@ struct sst_cmd_set_gain_dual {
struct sst_cmd_set_params {
struct sst_destination_id dst;
u16 command_id;
- char params[0];
+ char params[];
} __packed;
diff --git a/sound/soc/intel/skylake/skl-i2s.h b/sound/soc/intel/skylake/skl-i2s.h
index d7c15873c0d4..dfce91e11be1 100644
--- a/sound/soc/intel/skylake/skl-i2s.h
+++ b/sound/soc/intel/skylake/skl-i2s.h
@@ -46,7 +46,7 @@ struct skl_i2s_config_mclk {
struct skl_i2s_config_mclk_ext {
u32 mdivctrl;
u32 mdivr_count;
- u32 mdivr[0];
+ u32 mdivr[];
} __packed;
struct skl_i2s_config_blob_signature {
diff --git a/sound/soc/intel/skylake/skl-topology.h b/sound/soc/intel/skylake/skl-topology.h
index e967800dbb62..d2cd8ef8e97f 100644
--- a/sound/soc/intel/skylake/skl-topology.h
+++ b/sound/soc/intel/skylake/skl-topology.h
@@ -119,7 +119,7 @@ struct skl_cpr_gtw_cfg {
struct skl_dma_control {
u32 node_id;
u32 config_length;
- u32 config_data[0];
+ u32 config_data[];
} __packed;
struct skl_cpr_cfg {
@@ -152,7 +152,7 @@ struct skl_up_down_mixer_cfg {
struct skl_algo_cfg {
struct skl_base_cfg base_cfg;
- char params[0];
+ char params[];
} __packed;
struct skl_base_outfmt_cfg {
diff --git a/sound/soc/intel/skylake/skl.h b/sound/soc/intel/skylake/skl.h
index 2bfbf59277c4..26057f38a014 100644
--- a/sound/soc/intel/skylake/skl.h
+++ b/sound/soc/intel/skylake/skl.h
@@ -49,7 +49,7 @@ struct skl_astate_param {
struct skl_astate_config {
u32 count;
- struct skl_astate_param astate_table[0];
+ struct skl_astate_param astate_table[];
};
struct skl_fw_config {
