From: Baokun Li <libaokun1@xxxxxxxxxx> [ Upstream commit fad7cd3310db3099f95dd34312c77740fbc455e5 ] 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> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210804021212.990223-1-libaokun1@xxxxxxxxxx [axboe: dropped unlikely()] Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/block/nbd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 1061894a55df..7384058c24d0 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1369,6 +1369,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, unsigned int cmd, unsigned long arg) { struct nbd_config *config = nbd->config; + loff_t bytesize; switch (cmd) { case NBD_DISCONNECT: @@ -1383,8 +1384,9 @@ 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: - return nbd_set_size(nbd, arg * config->blksize, - config->blksize); + if (check_mul_overflow((loff_t)arg, config->blksize, &bytesize)) + return -EINVAL; + return nbd_set_size(nbd, bytesize, config->blksize); case NBD_SET_TIMEOUT: nbd_set_cmd_timeout(nbd, arg); return 0; -- 2.30.2
