On 7/30/21 7:48 PM, Baokun Li wrote: > If user specify a large enough value of NBD blocks option, it may trigger > signed integer overflow which may lead to nbd->config->bytesize becomes a > large or small value, zero in particular. > > UBSAN: Undefined behaviour in drivers/block/nbd.c:325:31 > signed integer overflow: > 1024 * 4611686155866341414 cannot be represented in type 'long long int' > [...] > Call trace: > [...] > handle_overflow+0x188/0x1dc lib/ubsan.c:192 > __ubsan_handle_mul_overflow+0x34/0x44 lib/ubsan.c:213 > nbd_size_set drivers/block/nbd.c:325 [inline] > __nbd_ioctl drivers/block/nbd.c:1342 [inline] > nbd_ioctl+0x998/0xa10 drivers/block/nbd.c:1395 > __blkdev_driver_ioctl block/ioctl.c:311 [inline] > [...] > > Although it is not a big deal, still silence the UBSAN by limit > the input value. > > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx> > Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> > --- > drivers/block/nbd.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index c38317979f74..7c838bf8cc31 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -1398,6 +1398,8 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, > case NBD_SET_SIZE: > return nbd_set_size(nbd, arg, config->blksize); > case NBD_SET_SIZE_BLOCKS: > + if (arg && (LLONG_MAX / arg <= config->blksize)) > + return -EINVAL; Use check_mul_overflow() instead? -- Jens Axboe
