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Commit 7f1855c7 authored by Marc Zyngier's avatar Marc Zyngier Committed by shaohanlin
Browse files

HID: core: Correctly handle ReportSize being zero 



commit bce1305c0ece3dc549663605e567655dd701752c upstream.

It appears that a ReportSize value of zero is legal, even if a bit
non-sensical. Most of the HID code seems to handle that gracefully,
except when computing the total size in bytes. When fed as input to
memset, this leads to some funky outcomes.

Detect the corner case and correctly compute the size.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarBenjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from commit cf7797ea)
parent cf8bee4e

drivers/hid/hid-core.c

+13 −2
Original line number Diff line number Diff line
@@ -1406,6 +1406,17 @@ static void hid_output_field(const struct hid_device *hid, 
	}

}



/*

 * Compute the size of a report.

 */

static size_t hid_compute_report_size(struct hid_report *report)

{

	if (report->size)

		return ((report->size - 1) >> 3) + 1;



	return 0;

}



/*

 * Create a report. 'data' has to be allocated using

 * hid_alloc_report_buf() so that it has proper size.
@@ -1418,7 +1429,7 @@ void hid_output_report(struct hid_report *report, __u8 *data) 
	if (report->id > 0)

		*data++ = report->id;



	memset(data, 0, ((report->size - 1) >> 3) + 1);

	memset(data, 0, hid_compute_report_size(report));

	for (n = 0; n < report->maxfield; n++)

		hid_output_field(report->device, report->field[n], data);

}
@@ -1545,7 +1556,7 @@ int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size, 
		csize--;

	}



	rsize = ((report->size - 1) >> 3) + 1;

	rsize = hid_compute_report_size(report);



	if (report_enum->numbered && rsize >= HID_MAX_BUFFER_SIZE)

		rsize = HID_MAX_BUFFER_SIZE - 1;