From: Anirudh Rayabharam mail@anirudhrb.com

stable inclusion from stable-v5.15.128 commit 0e280502be1b003c3483ae03fc60dea554fcfa82 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I93XA7 CVE: CVE-2021-46906

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 6be388f4a35d2ce5ef7dbf635a8964a5da7f799f ]

In hid_submit_ctrl(), the way of calculating the report length doesn't take into account that report->size can be zero. When running the syzkaller reproducer, a report of size 0 causes hid_submit_ctrl) to calculate transfer_buffer_length as 16384. When this urb is passed to the usb core layer, KMSAN reports an info leak of 16384 bytes.

To fix this, first modify hid_report_len() to account for the zero report size case by using DIV_ROUND_UP for the division. Then, call it from hid_submit_ctrl().

Reported-by: syzbot+7c2bb71996f95a82524c@syzkaller.appspotmail.com Signed-off-by: Anirudh Rayabharam mail@anirudhrb.com Acked-by: Benjamin Tissoires benjamin.tissoires@redhat.com Signed-off-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yu Liao liaoyu15@huawei.com --- drivers/hid/usbhid/hid-core.c | 2 +- include/linux/hid.h | 3 +-- 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c index 11103efebbaa..2376740ce4d5 100644 --- a/drivers/hid/usbhid/hid-core.c +++ b/drivers/hid/usbhid/hid-core.c @@ -377,7 +377,7 @@ static int hid_submit_ctrl(struct hid_device *hid) raw_report = usbhid->ctrl[usbhid->ctrltail].raw_report; dir = usbhid->ctrl[usbhid->ctrltail].dir;

- len = ((report->size - 1) >> 3) + 1 + (report->id > 0); + len = hid_report_len(report); if (dir == USB_DIR_OUT) { usbhid->urbctrl->pipe = usb_sndctrlpipe(hid_to_usb_dev(hid), 0); usbhid->urbctrl->transfer_buffer_length = len; diff --git a/include/linux/hid.h b/include/linux/hid.h index 7f321909ec58..2053f3ee4395 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -1154,8 +1154,7 @@ static inline void hid_hw_wait(struct hid_device *hdev) */ static inline u32 hid_report_len(struct hid_report *report) { - /* equivalent to DIV_ROUND_UP(report->size, 8) + !!(report->id > 0) */ - return ((report->size - 1) >> 3) + 1 + (report->id > 0); + return DIV_ROUND_UP(report->size, 8) + (report->id > 0); }

int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size,