| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 32/88] HID: core: fix off-by-one memset in hid_report_raw_event() | Date | Tue, 10 Mar 2020 13:38:40 +0100 |
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From: Johan Korsnes <jkorsnes@cisco.com>
commit 5ebdffd25098898aff1249ae2f7dbfddd76d8f8f upstream.
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. hid_report_raw_event() is an exported symbol, so presumabely we cannot always rely on this being the case.
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> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/hid/hid-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1547,7 +1547,9 @@ int hid_report_raw_event(struct hid_devi 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) {
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