================================================================== BUG: KASAN: stack-out-of-bounds in iov_iter_advance+0x4b3/0x4f0 lib/iov_iter.c:491 Read of size 8 at addr ffff8800b3027a50 by task syz-executor.5/12700 CPU: 0 PID: 12700 Comm: syz-executor.5 Not tainted 4.4.174+ #4 0000000000000000 d45fa023dde4492e ffff8800b3027700 ffffffff81aad1a1 0000000000000000 ffffea0002cc09c0 ffff8800b3027a50 0000000000000008 ffff8800b3027a48 ffff8800b3027738 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 [] __kernel_write+0x112/0x370 fs/read_write.c:513 [] write_pipe_buf+0x15d/0x1f0 fs/splice.c:1074 [] splice_from_pipe_feed fs/splice.c:776 [inline] [] __splice_from_pipe+0x37e/0x7a0 fs/splice.c:901 [] splice_from_pipe+0x108/0x170 fs/splice.c:936 [] default_file_splice_write+0x3c/0x80 fs/splice.c:1086 [] do_splice_from fs/splice.c:1128 [inline] [] do_splice fs/splice.c:1404 [inline] [] SYSC_splice fs/splice.c:1707 [inline] [] SyS_splice+0xd71/0x13a0 fs/splice.c:1690 [] entry_SYSCALL_64_fastpath+0x1e/0x9a The buggy address belongs to the page: page:ffffea0002cc09c0 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x0() page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8800b3027900: f2 f2 f2 00 00 00 00 00 00 00 f3 f3 f3 f3 f3 00 ffff8800b3027980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8800b3027a00: 00 00 00 f1 f1 f1 f1 00 00 f2 f2 00 00 00 00 00 ^ ffff8800b3027a80: f2 f2 f2 f2 f2 00 00 00 00 00 f3 f3 f3 f3 f3 00 ffff8800b3027b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================