Description
In the Linux kernel, the following vulnerability has been resolved: 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.
Product status
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 52851d0c3354b397c11d31dfeb8b2a2fc85a0002
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before fab766c8a1aff715bce7075aab40e780266f8e1a
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before ffb75ffaa68723276365d0f9d00b03362b750657
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 55793ea54d77719a071b1ccc05a05056e3b5e009
5.15.113
6.1.30
6.3.4
6.4
References
git.kernel.org/...c/52851d0c3354b397c11d31dfeb8b2a2fc85a0002
git.kernel.org/...c/fab766c8a1aff715bce7075aab40e780266f8e1a
git.kernel.org/...c/ffb75ffaa68723276365d0f9d00b03362b750657
git.kernel.org/...c/55793ea54d77719a071b1ccc05a05056e3b5e009
