HID: hyperv: make pointer arithmetics understandable for FORTIFY_SOURCE

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Commit 83df7b5fa6 ("HID: hyperv: add KUnit coverage for device info
bounds") introduced this piece of code

	report = ((u8 *)&info->hid_descriptor) + info->hid_descriptor.bLength;
	memset(report, 0x42, 4);

to populate the report, making use of the fact that the report
&info->hid_descriptor points to a struct hid_descriptor (which is a fixed-size
struct).

GCC's FORTIFY_SOURCE infer the object size from that specific struct field
rather than the outer dynamically allocated info buffer. As a result, writing
past sizeof(struct hid_descriptor) triggers the __write_overflow_field warning.

Calculate the pointer offset using info directly, so the compiler evaluates the
memory bounds against the allocated flexible layout of struct
synthhid_device_info instead of the nested struct.

Fixes: 83df7b5fa6 ("HID: hyperv: add KUnit coverage for device info bounds")
Reported-by: Jürgen Groß <jgross@suse.com>
Tested-by: Jürgen Groß <jgross@suse.com>
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

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This commit is contained in:

Jiri Kosina 2026-08-21 15:39:15 +02:00 • committed by Jiri Kosina

parent 445fcd33c5

commit d0ad81b2b5

1 changed files with 2 additions and 2 deletions

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drivers/hid/hid-hyperv.c

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