| Message ID | tencent_5E4FB78DACA5F90D97926A5DBE5D96993007@qq.com |
|---|---|
| State | New |
| Headers | show |
| Series | [V2] USB: usbtmc: prevent kernel-usb-infoleak | expand |
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c index 6bd9fe565385..faf8c5508997 100644 --- a/drivers/usb/class/usbtmc.c +++ b/drivers/usb/class/usbtmc.c @@ -1591,6 +1591,10 @@ static ssize_t usbtmc_write(struct file *filp, const char __user *buf, goto exit; } + if (aligned < buflen && (transfersize % 4)) + memset(&buffer[USBTMC_HEADER_SIZE + transfersize], 0, + aligned - USBTMC_HEADER_SIZE - transfersize); + dev_dbg(&data->intf->dev, "%s(size:%u align:%u)\n", __func__, (unsigned int)transfersize, (unsigned int)aligned);
The syzbot reported a kernel-usb-infoleak in usbtmc_write. The expression "aligned = (transfersize + (USBTMC_HEADER_SIZE + 3)) & ~3;" in usbtmcw_write() follows the following pattern: aligned = (1 + 12 + 3) & ~3 = 16 // 3 bytes have not been initialized aligned = (2 + 12 + 3) & ~3 = 16 // 2 bytes have not been initialized aligned = (3 + 12 + 3) & ~3 = 16 // 1 byte has not been initialized aligned = (4 + 12 + 3) & ~3 = 16 // All bytes have been initialized aligned = (5 + 12 + 3) & ~3 = 20 // 3 bytes have not been initialized aligned = (6 + 12 + 3) & ~3 = 20 // 2 bytes have not been initialized aligned = (7 + 12 + 3) & ~3 = 20 // 1 byte has not been initialized aligned = (8 + 12 + 3) & ~3 = 20 // All bytes have been initialized aligned = (9 + 12 + 3) & ~3 = 24 ... Note: #define USBTMC_HEADER_SIZE 12 This results in the buffer[USBTMC_SEAD_SIZE+transfersize] and its subsequent memory not being initialized. The condition aligned < buflen is used to avoid out of bounds access to the buffer[USBTMC_HEADER_SIZE + transfersize] when "transfersize = buflen - USBTMC_HEADER_SIZE". Fixes: 4ddc645f40e9 ("usb: usbtmc: Add ioctl for vendor specific write") Reported-and-tested-by: syzbot+9d34f80f841e948c3fdb@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9d34f80f841e948c3fdb Signed-off-by: Edward Adam Davis <eadavis@qq.com> --- drivers/usb/class/usbtmc.c | 4 ++++ 1 file changed, 4 insertions(+)