Re: Build error with kernel from 2026-08-21

On Fri, 21 Aug 2026, Jiri Kosina wrote:

> > >>> make[3]: *** [/home/gross/linux/head/scripts/Makefile.build:550: drivers]
> > >>> Error 2
> > >>> make[1]: Leaving directory '/home/gross/linux/head/jg/build/x86_32-yes'
> > >>> make[2]: *** [/home/gross/linux/head/Makefile:2193: .] Error 2
> > >>> make[1]: *** [/home/gross/linux/head/Makefile:248: __sub-make] Error 2
> > >>> make: *** [Makefile:248: __sub-make] Error 2
> > >>> [msr]~/linux/head> mk x86_32-yes
> > >>> make O=jg/build/x86_32-yes CC=gcc-13 PYTHON3=python3.11
> > >>> make[1]: Entering directory '/home/gross/linux/head/jg/build/x86_32-yes'
> > >>>   CC      drivers/hid/hid-hyperv.o
> > >>> In file included from /home/gross/linux/head/include/linux/string.h:383,
> > >>>                    from
> > >>>   /home/gross/linux/head/arch/x86/include/asm/page_32.h:18,
> > >>>                    from
> > >>>   /home/gross/linux/head/arch/x86/include/asm/page.h:14,
> > >>>                    from
> > >>>   /home/gross/linux/head/arch/x86/include/asm/processor.h:20,
> > >>>                    from
> > >>>   /home/gross/linux/head/arch/x86/include/asm/timex.h:5,
> > >>>                    from /home/gross/linux/head/include/linux/timex.h:67,
> > >>>                    from /home/gross/linux/head/include/linux/time32.h:13,
> > >>>                    from /home/gross/linux/head/include/linux/time.h:60,
> > >>>                    from /home/gross/linux/head/include/linux/stat.h:19,
> > >>>                    from /home/gross/linux/head/include/linux/module.h:13,
> > >>>                    from /home/gross/linux/head/drivers/hid/hid-hyperv.c:8:
> > >>> In function ‘fortify_memset_chk’,
> > >>>     inlined from ‘mousevsc_device_info_valid_descriptor’ at
> > >>> /home/gross/linux/ head/drivers/hid/hid-hyperv.c:691:2:
> > >>> /home/gross/linux/head/include/linux/fortify-string.h:430:25: error: call
> > >>> to
> > >>> ‘__write_overflow_field’ declared with attribute warning: detected write
> > >>> beyond size of field (1st parameter); maybe use struct_group()?
> > >>> [-Werror=attribute- warning]
> > >>>     430 |                         __write_overflow_field(p_size_field,
> > >>>   size);
> > >>>         |                        
> > >>>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >>> In function ‘fortify_memset_chk’,
> > >>>     inlined from ‘mousevsc_device_info_report_desc_oob’ at
> > >>> /home/gross/linux/ head/drivers/hid/hid-hyperv.c:717:2:
> > >>> /home/gross/linux/head/include/linux/fortify-string.h:430:25: error: call
> > >>> to
> > >>> ‘__write_overflow_field’ declared with attribute warning: detected write
> > >>> beyond size of field (1st parameter); maybe use struct_group()?
> > >>> [-Werror=attribute- warning]
> > >>>     430 |                         __write_overflow_field(p_size_field,
> > >>>   size);
> > >>>         |                        
> > >>>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >>> cc1: all warnings being treated as errors
> > >>> make[5]: *** [/home/gross/linux/head/scripts/Makefile.build:290:
> > >>> drivers/hid/ hid-hyperv.o] Error 1
> > >>> make[4]: *** [/home/gross/linux/head/scripts/Makefile.build:550:
> > >>> drivers/hid] Error 2
> > >>> make[3]: *** [/home/gross/linux/head/scripts/Makefile.build:550: drivers]
> > >>> Error 2
> > >>> make[2]: *** [/home/gross/linux/head/Makefile:2193: .] Error 2
> > >>> make[1]: Leaving directory '/home/gross/linux/head/jg/build/x86_32-yes'
> > >>> make[1]: *** [/home/gross/linux/head/Makefile:248: __sub-make] Error 2
> > >>> make: *** [Makefile:248: __sub-make] Error 2
> > >>
> > >> A git bisect flagged commit 83df7b5fa6735b5084ecd296a0f67208650ba497 to be
> > >> the
> > >> problematic patch.
> > > 
> > > Hi,
> > > 
> > > this was reported by syzbot two days ago. I asked it to test a candidate
> > > fix [1], but it never responded back. Can you give it a quick shot in your
> > > 32bit build environment, please?
> > > 
> > > Thanks.
> > > 
> > > [1]
> > > https://lore.kernel.org/all/[email protected]/
> > > 
> > 
> > BTW, I'm seeing the build failure in 64-bit environment, too.
> 
> Ah, that's actually a different issue than the syzbot-reported one. I'll 
> look into this one after I am done with the other build failure introduced 
> by the same commit.

Can you please test the one below? Thanks.

diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
index 6579bd19da13..4a10b24da9fa 100644
--- a/drivers/hid/hid-hyperv.c
+++ b/drivers/hid/hid-hyperv.c
@@ -687,7 +687,7 @@ static void mousevsc_device_info_valid_descriptor(struct kunit *test)
 
 	info->hid_descriptor.bLength = sizeof(struct hid_descriptor);
 	info->hid_descriptor.rpt_desc.wDescriptorLength = cpu_to_le16(4);
-	report = ((u8 *)&info->hid_descriptor) + info->hid_descriptor.bLength;
+	report = (u8 *)info + offsetof(struct synthhid_device_info, hid_descriptor) + info->hid_descriptor.bLength;
 	memset(report, 0x42, 4);
 
 	mousevsc_on_receive_device_info(input_dev, info, sizeof(*info) + 4);
@@ -713,7 +713,7 @@ static void mousevsc_device_info_report_desc_oob(struct kunit *test)
 
 	info->hid_descriptor.bLength = sizeof(struct hid_descriptor);
 	info->hid_descriptor.rpt_desc.wDescriptorLength = cpu_to_le16(64);
-	report = ((u8 *)&info->hid_descriptor) + info->hid_descriptor.bLength;
+	report = (u8 *)info + offsetof(struct synthhid_device_info, hid_descriptor) + info->hid_descriptor.bLength;
 	memset(report, 0x42, 8);
 
 	mousevsc_on_receive_device_info(input_dev, info, sizeof(*info) + 8);

-- 
Jiri Kosina
SUSE Labs