From: Marc Zyngier maz@kernel.org
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: Marc Zyngier maz@kernel.org Signed-off-by: Benjamin Tissoires benjamin.tissoires@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/hid/hid-core.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)
--- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1426,6 +1426,17 @@ static void hid_output_field(const struc }
/* + * 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. */ @@ -1437,7 +1448,7 @@ void hid_output_report(struct hid_report 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); } @@ -1564,7 +1575,7 @@ int hid_report_raw_event(struct hid_devi 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;