input: syz1 as /devices/virtual/input/input4271 ================================================================== BUG: KASAN: stack-out-of-bounds in iov_iter_advance+0x4b3/0x4f0 lib/iov_iter.c:491 Read of size 8 at addr ffff8800b8d0fd60 by task syz-executor.0/6453 CPU: 1 PID: 6453 Comm: syz-executor.0 Not tainted 4.4.174+ #4 0000000000000000 914645c77c7ecb0f ffff8800b8d0fa10 ffffffff81aad1a1 0000000000000000 ffffea0002e343c0 ffff8800b8d0fd60 0000000000000008 ffff8800b8d0fd58 ffff8800b8d0fa48 ffffffff81490120 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [] print_address_description+0x6f/0x21b mm/kasan/report.c:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report mm/kasan/report.c:408 [inline] [] kasan_report.cold+0x8c/0x2be mm/kasan/report.c:393 [] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429 [] iov_iter_advance+0x4b3/0x4f0 lib/iov_iter.c:491 [] tun_get_user+0x2c6/0x2640 drivers/net/tun.c:1124 [] tun_chr_write_iter+0xda/0x190 drivers/net/tun.c:1283 [] new_sync_write fs/read_write.c:480 [inline] [] __vfs_write+0x2e8/0x3d0 fs/read_write.c:493 [] vfs_write+0x182/0x4e0 fs/read_write.c:540 [] SYSC_write fs/read_write.c:587 [inline] [] SyS_write+0xdc/0x1c0 fs/read_write.c:579 [] entry_SYSCALL_64_fastpath+0x1e/0x9a The buggy address belongs to the page: page:ffffea0002e343c0 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x0() page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8800b8d0fc00: f2 f2 f2 f2 f2 00 00 00 00 00 00 00 f3 f3 f3 f3 ffff8800b8d0fc80: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8800b8d0fd00: 00 00 00 00 00 f1 f1 f1 f1 00 00 f2 f2 00 00 00 ^ ffff8800b8d0fd80: 00 00 f2 f2 f2 f2 f2 00 00 00 00 00 f3 f3 f3 f3 ffff8800b8d0fe00: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================