[PATCH AUTOSEL 5.15 43/47] usb: idmouse: fix an uninit-value in idmouse_open

Sasha Levin
2022-10-13T00:32:59Z

From: Dongliang Mu <mudongliangabcd@gmail.com>

[ Upstream commit bce2b0539933e485d22d6f6f076c0fcd6f185c4c ]

In idmouse_create_image, if any ftip_command fails, it will
go to the reset label. However, this leads to the data in
bulk_in_buffer[HEADER..IMGSIZE] uninitialized. And the check
for valid image incurs an uninitialized dereference.

Fix this by moving the check before reset label since this
check only be valid if the data after bulk_in_buffer[HEADER]
has concrete data.

Note that this is found by KMSAN, so only kernel compilation
is tested.

Reported-by: syzbot+79832d33eb89fb3cd092@syzkaller.appspotmail.com
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Link: https://lore.kernel.org/r/20220922134847.1101921-1-dzm91@hust.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/usb/misc/idmouse.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/misc/idmouse.c b/drivers/usb/misc/idmouse.c
index e9437a176518..ea39243efee3 100644
--- a/drivers/usb/misc/idmouse.c
+++ b/drivers/usb/misc/idmouse.c
@@ -177,10 +177,6 @@ static int idmouse_create_image(struct usb_idmouse *dev)
bytes_read += bulk_read;
}

- /* reset the device */
-reset:
- ftip_command(dev, FTIP_RELEASE, 0, 0);
-
/* check for valid image */
/* right border should be black (0x00) */
for (bytes_read = sizeof(HEADER)-1 + WIDTH-1; bytes_read < IMGSIZE; bytes_read += WIDTH)
@@ -192,6 +188,10 @@ static int idmouse_create_image(struct usb_idmouse *dev)
if (dev->bulk_in_buffer[bytes_read] != 0xFF)
return -EAGAIN;

+ /* reset the device */
+reset:
+ ftip_command(dev, FTIP_RELEASE, 0, 0);
+
/* should be IMGSIZE == 65040 */
dev_dbg(&dev->interface->dev, "read %d bytes fingerprint data\n",
bytes_read);
--
2.35.1