| Message ID | 20200115123344.4650-1-jkorsnes@cisco.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/2] HID: core: fix off-by-one memset in hid_report_raw_event() | expand |
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 851fe54ea59e..359616e3efbb 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1741,7 +1741,9 @@ int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size, rsize = ((report->size - 1) >> 3) + 1; - if (rsize > HID_MAX_BUFFER_SIZE) + if (report_enum->numbered && rsize >= HID_MAX_BUFFER_SIZE) + rsize = HID_MAX_BUFFER_SIZE - 1; + else if (rsize > HID_MAX_BUFFER_SIZE) rsize = HID_MAX_BUFFER_SIZE; if (csize < rsize) {
In case a report is greater than HID_MAX_BUFFER_SIZE it is truncated, but the report-number byte is not correctly handled. This results in a off-by-one in the following memset, causing a kernel Oops and ensuing system crash. Note: With commit 8ec321e96e05 ("HID: Fix slab-out-of-bounds read in hid_field_extract") I no longer hit the kernel Oops as we instead fail "controlled" at probe if there is a report too long in the HID report descriptor. I still believe this is worth fixing though, as hid_report_raw_event() should have its logic correct. But if we fail at probe for too large reports, a better solution might be to remove this truncation logic entirely. Fixes: 966922f26c7f ("HID: fix a crash in hid_report_raw_event() function.") Signed-off-by: Johan Korsnes <jkorsnes@cisco.com> Cc: Armando Visconti <armando.visconti@st.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Alan Stern <stern@rowland.harvard.edu> --- drivers/hid/hid-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)