From: Pavel Skripkin paskripkin@gmail.com
[ Upstream commit d668769eb9c52b150753f1653f7f5a0aeb8239d2 ]
Syzbot reported uninit value in mcs7830_bind(). The problem was in missing validation check for bytes read via usbnet_read_cmd().
usbnet_read_cmd() internally calls usb_control_msg(), that returns number of bytes read. Code should validate that requested number of bytes was actually read.
So, this patch adds missing size validation check inside mcs7830_get_reg() to prevent uninit value bugs
Reported-and-tested-by: syzbot+003c0a286b9af5412510@syzkaller.appspotmail.com Fixes: 2a36d7083438 ("USB: driver for mcs7830 (aka DeLOCK) USB ethernet adapter") Signed-off-by: Pavel Skripkin paskripkin@gmail.com Reviewed-by: Arnd Bergmann arnd@arndb.de Link: https://lore.kernel.org/r/20220106225716.7425-1-paskripkin@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/usb/mcs7830.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/net/usb/mcs7830.c b/drivers/net/usb/mcs7830.c index 4f345bd4e6e29..95151b46f2001 100644 --- a/drivers/net/usb/mcs7830.c +++ b/drivers/net/usb/mcs7830.c @@ -121,8 +121,16 @@ static const char driver_name[] = "MOSCHIP usb-ethernet driver";
static int mcs7830_get_reg(struct usbnet *dev, u16 index, u16 size, void *data) { - return usbnet_read_cmd(dev, MCS7830_RD_BREQ, MCS7830_RD_BMREQ, - 0x0000, index, data, size); + int ret; + + ret = usbnet_read_cmd(dev, MCS7830_RD_BREQ, MCS7830_RD_BMREQ, + 0x0000, index, data, size); + if (ret < 0) + return ret; + else if (ret < size) + return -ENODATA; + + return ret; }
static int mcs7830_set_reg(struct usbnet *dev, u16 index, u16 size, const void *data)