[v2] ALSA: asihpi: avoid write overflow check warning

[PATCH] [v2] ALSA: asihpi: avoid write overflow check warning

Posted by Arnd Bergmann 2 weeks, 5 days ago

From: Arnd Bergmann <arnd@arndb.de>

clang-22 rightfully warns that the memcpy() in adapter_prepare() copies
between different structures, crossing the boundary of nested
structures inside it:

In file included from sound/pci/asihpi/hpimsgx.c:13:
In file included from include/linux/string.h:386:
include/linux/fortify-string.h:569:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
  569 |                         __write_overflow_field(p_size_field, size);

The two structures seem to refer to the same layout, despite the
separate definitions, so the code is in fact correct.

Avoid the warning by copying the two inner structures separately.
I see the same pattern happens in other functions in the same file,
so there is a chance that this may come back in the future, but
this instance is the only one that I saw in practice, hitting it
multiple times per day in randconfig build.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---

v2: use correct union member
---
 sound/pci/asihpi/hpimsgx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/sound/pci/asihpi/hpimsgx.c b/sound/pci/asihpi/hpimsgx.c
index b68e6bfbbfba..ed1c7b774436 100644
--- a/sound/pci/asihpi/hpimsgx.c
+++ b/sound/pci/asihpi/hpimsgx.c
@@ -581,8 +581,10 @@ static u16 adapter_prepare(u16 adapter)
 		HPI_ADAPTER_OPEN);
 	hm.adapter_index = adapter;
 	hw_entry_point(&hm, &hr);
-	memcpy(&rESP_HPI_ADAPTER_OPEN[adapter], &hr,
-		sizeof(rESP_HPI_ADAPTER_OPEN[0]));
+	memcpy(&rESP_HPI_ADAPTER_OPEN[adapter].h, &hr,
+		sizeof(rESP_HPI_ADAPTER_OPEN[adapter].h));
+	memcpy(&rESP_HPI_ADAPTER_OPEN[adapter].a, &hr.u.ax.info,
+		sizeof(rESP_HPI_ADAPTER_OPEN[adapter].a));
 	if (hr.error)
 		return hr.error;
 
-- 
2.39.5

Re: [PATCH] [v2] ALSA: asihpi: avoid write overflow check warning

Posted by Takashi Iwai 2 weeks, 5 days ago

On Wed, 18 Mar 2026 13:40:07 +0100,
Arnd Bergmann wrote:
> 
> From: Arnd Bergmann <arnd@arndb.de>
> 
> clang-22 rightfully warns that the memcpy() in adapter_prepare() copies
> between different structures, crossing the boundary of nested
> structures inside it:
> 
> In file included from sound/pci/asihpi/hpimsgx.c:13:
> In file included from include/linux/string.h:386:
> include/linux/fortify-string.h:569:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
>   569 |                         __write_overflow_field(p_size_field, size);
> 
> The two structures seem to refer to the same layout, despite the
> separate definitions, so the code is in fact correct.
> 
> Avoid the warning by copying the two inner structures separately.
> I see the same pattern happens in other functions in the same file,
> so there is a chance that this may come back in the future, but
> this instance is the only one that I saw in practice, hitting it
> multiple times per day in randconfig build.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> 
> v2: use correct union member

Applied now.  Thanks.


Takashi