On 8/3/21 8:12 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. Applied with unlikely() removed. -- Jens Axboe
