From: Zhong Jinghua Date: Mon, 6 Feb 2023 14:58:05 +0000 (+0800) Subject: nbd: fix incomplete validation of ioctl arg X-Git-Tag: v6.6.7~2880^2~16 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=55793ea54d77719a071b1ccc05a05056e3b5e009;p=platform%2Fkernel%2Flinux-starfive.git nbd: fix incomplete validation of ioctl arg We tested and found an alarm caused by nbd_ioctl arg without verification. The UBSAN warning calltrace like below: UBSAN: Undefined behaviour in fs/buffer.c:1709:35 signed integer overflow: -9223372036854775808 - 1 cannot be represented in type 'long long int' CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78 show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x170/0x1dc lib/dump_stack.c:118 ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161 handle_overflow+0x188/0x1dc lib/ubsan.c:192 __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206 __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709 block_write_full_page+0x1f0/0x280 fs/buffer.c:2934 blkdev_writepage+0x34/0x40 fs/block_dev.c:607 __writepage+0x68/0xe8 mm/page-writeback.c:2305 write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240 generic_writepages+0xdc/0x148 mm/page-writeback.c:2329 blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114 do_writepages+0xd4/0x250 mm/page-writeback.c:2344 The reason for triggering this warning is __block_write_full_page() -> i_size_read(inode) - 1 overflow. inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize. We think it is necessary to limit the size of arg to prevent errors. Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int. Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine), it will become 1 after the coercion, which will return unexpected results. Fix it by adding checks to prevent passing in too large numbers. Signed-off-by: Zhong Jinghua Reviewed-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20230206145805.2645671-1-zhongjinghua@huawei.com Signed-off-by: Jens Axboe --- diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index c0b1611..d445fd0 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -325,6 +325,9 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize, if (blk_validate_block_size(blksize)) return -EINVAL; + if (bytesize < 0) + return -EINVAL; + nbd->config->bytesize = bytesize; nbd->config->blksize_bits = __ffs(blksize); @@ -1111,6 +1114,9 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg, struct nbd_sock *nsock; int err; + /* Arg will be cast to int, check it to avoid overflow */ + if (arg > INT_MAX) + return -EINVAL; sock = nbd_get_socket(nbd, arg, &err); if (!sock) return err;