One-element arrays are deprecated, and we are replacing them with flexible
array members instead. However, in this case it seems those one-element
arrays have never actually been used as fake flexible arrays.
See this code that dates from Linux-2.6.12-rc2 initial git repository build
(commit 1da177e4c3f4 ("Linux-2.6.12-rc2")):
sound/pci/mixart/mixart_core.h:
215 struct mixart_stream_state_req
216 {
217 u32 delayed;
218 u64 scheduler;
219 u32 reserved4np[3];
220 u32 stream_count; /* set to 1 for instance */
221 struct mixart_flow_info stream_info; /* could be an array[stream_count] */
222 } __attribute__((packed));
sound/pci/mixart/mixart.c:
388
389 memset(&stream_state_req, 0, sizeof(stream_state_req));
390 stream_state_req.stream_count = 1;
391 stream_state_req.stream_info.stream_desc.uid_pipe = stream->pipe->group_uid;
392 stream_state_req.stream_info.stream_desc.stream_idx = stream->substream->number;
393
So, taking the code above as example, replace multiple one-element
arrays with simple object declarations, and refactor the rest of the
code, accordingly.
This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [1].
This results in no differences in binary output.
Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/296
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
Changes in v2:
- Keep the code comments (by Takashi Iwai) and explicitly mention that
the objects could be arrays, in theory.
v1:
- Link: https://lore.kernel.org/linux-hardening/ZGVlcpuvx1rSOMP8@work/
sound/pci/mixart/mixart.c | 8 ++++----
sound/pci/mixart/mixart_core.h | 7 +++----
2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/sound/pci/mixart/mixart.c b/sound/pci/mixart/mixart.c
index 1b078b789604..7ceaf6a7a77e 100644
--- a/sound/pci/mixart/mixart.c
+++ b/sound/pci/mixart/mixart.c
@@ -98,7 +98,7 @@ static int mixart_set_pipe_state(struct mixart_mgr *mgr,
memset(&group_state, 0, sizeof(group_state));
group_state.pipe_count = 1;
- group_state.pipe_uid[0] = pipe->group_uid;
+ group_state.pipe_uid = pipe->group_uid;
if(start)
request.message_id = MSG_STREAM_START_STREAM_GRP_PACKET;
@@ -185,7 +185,7 @@ static int mixart_set_clock(struct mixart_mgr *mgr,
clock_properties.clock_mode = CM_STANDALONE;
clock_properties.frequency = rate;
clock_properties.nb_callers = 1; /* only one entry in uid_caller ! */
- clock_properties.uid_caller[0] = pipe->group_uid;
+ clock_properties.uid_caller = pipe->group_uid;
dev_dbg(&mgr->pci->dev, "mixart_set_clock to %d kHz\n", rate);
@@ -565,8 +565,8 @@ static int mixart_set_format(struct mixart_stream *stream, snd_pcm_format_t form
stream_param.pipe_count = 1; /* set to 1 */
stream_param.stream_count = 1; /* set to 1 */
- stream_param.stream_desc[0].uid_pipe = stream->pipe->group_uid;
- stream_param.stream_desc[0].stream_idx = stream->substream->number;
+ stream_param.stream_desc.uid_pipe = stream->pipe->group_uid;
+ stream_param.stream_desc.stream_idx = stream->substream->number;
request.message_id = MSG_STREAM_SET_INPUT_STAGE_PARAM;
request.uid = (struct mixart_uid){0,0};
diff --git a/sound/pci/mixart/mixart_core.h b/sound/pci/mixart/mixart_core.h
index 2f0e29ed5d63..d39233e0e070 100644
--- a/sound/pci/mixart/mixart_core.h
+++ b/sound/pci/mixart/mixart_core.h
@@ -231,7 +231,7 @@ struct mixart_group_state_req
u64 scheduler;
u32 reserved4np[2];
u32 pipe_count; /* set to 1 for instance */
- struct mixart_uid pipe_uid[1]; /* could be an array[pipe_count] */
+ struct mixart_uid pipe_uid; /* could be an array[pipe_count], in theory */
} __attribute__((packed));
struct mixart_group_state_resp
@@ -314,7 +314,7 @@ struct mixart_clock_properties
u32 format;
u32 board_mask;
u32 nb_callers; /* set to 1 (see below) */
- struct mixart_uid uid_caller[1];
+ struct mixart_uid uid_caller;
} __attribute__((packed));
struct mixart_clock_properties_resp
@@ -401,8 +401,7 @@ struct mixart_stream_param_desc
u32 reserved4np[3];
u32 pipe_count; /* set to 1 (array size !) */
u32 stream_count; /* set to 1 (array size !) */
- struct mixart_txx_stream_desc stream_desc[1]; /* only one stream per command, but this could be an array */
-
+ struct mixart_txx_stream_desc stream_desc; /* only one stream per command, but this could be an array, in theory */
} __attribute__((packed));
--
2.34.1
On Fri, 19 May 2023 22:54:46 +0200,
Gustavo A. R. Silva wrote:
>
> One-element arrays are deprecated, and we are replacing them with flexible
> array members instead. However, in this case it seems those one-element
> arrays have never actually been used as fake flexible arrays.
>
> See this code that dates from Linux-2.6.12-rc2 initial git repository build
> (commit 1da177e4c3f4 ("Linux-2.6.12-rc2")):
>
> sound/pci/mixart/mixart_core.h:
> 215 struct mixart_stream_state_req
> 216 {
> 217 u32 delayed;
> 218 u64 scheduler;
> 219 u32 reserved4np[3];
> 220 u32 stream_count; /* set to 1 for instance */
> 221 struct mixart_flow_info stream_info; /* could be an array[stream_count] */
> 222 } __attribute__((packed));
>
> sound/pci/mixart/mixart.c:
> 388
> 389 memset(&stream_state_req, 0, sizeof(stream_state_req));
> 390 stream_state_req.stream_count = 1;
> 391 stream_state_req.stream_info.stream_desc.uid_pipe = stream->pipe->group_uid;
> 392 stream_state_req.stream_info.stream_desc.stream_idx = stream->substream->number;
> 393
>
> So, taking the code above as example, replace multiple one-element
> arrays with simple object declarations, and refactor the rest of the
> code, accordingly.
>
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [1].
>
> This results in no differences in binary output.
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/296
> Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
Thanks, applied.
Takashi