================================================================== BUG: KASAN: use-after-free in n_tty_check_throttle drivers/tty/n_tty.c:266 [inline] BUG: KASAN: use-after-free in n_tty_receive_buf_common+0x270f/0x2b70 drivers/tty/n_tty.c:1761 Read of size 1 at addr ffff88809dd02402 by task syz-executor478/9641 CPU: 1 PID: 9641 Comm: syz-executor478 Not tainted 5.5.0-rc2-next-20191220-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:639 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:132 n_tty_check_throttle drivers/tty/n_tty.c:266 [inline] n_tty_receive_buf_common+0x270f/0x2b70 drivers/tty/n_tty.c:1761 n_tty_receive_buf2+0x34/0x40 drivers/tty/n_tty.c:1777 tty_ldisc_receive_buf+0xad/0x1c0 drivers/tty/tty_buffer.c:461 paste_selection+0x1ff/0x460 drivers/tty/vt/selection.c:372 tioclinux+0x133/0x480 drivers/tty/vt/vt.c:3044 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441329 Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffed03ec0d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441329 RDX: 0000000020000000 RSI: 000000000000541c RDI: 0000000000000003 RBP: 000000000001af5a R08: 00000000004002c8 R09: 00000000004002c8 R10: 000000000000000d R11: 0000000000000246 R12: 00000000004020a0 R13: 0000000000402130 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 9643: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x163/0x770 mm/slab.c:3665 kmalloc_array include/linux/slab.h:597 [inline] set_selection_kernel+0x872/0x13b0 drivers/tty/vt/selection.c:305 set_selection_user+0x95/0xd9 drivers/tty/vt/selection.c:177 tioclinux+0x11c/0x480 drivers/tty/vt/vt.c:3039 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9644: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:335 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 set_selection_kernel+0x88f/0x13b0 drivers/tty/vt/selection.c:312 set_selection_user+0x95/0xd9 drivers/tty/vt/selection.c:177 tioclinux+0x11c/0x480 drivers/tty/vt/vt.c:3039 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:747 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff88809dd02400 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 2 bytes inside of 512-byte region [ffff88809dd02400, ffff88809dd02600) The buggy address belongs to the page: page:ffffea0002774080 refcount:1 mapcount:0 mapping:ffff8880aa400a80 index:0xffff88809dd02000 raw: 00fffe0000000200 ffffea00029cf908 ffffea00026a4088 ffff8880aa400a80 raw: ffff88809dd02000 ffff88809dd02000 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809dd02300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88809dd02380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88809dd02400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88809dd02480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809dd02500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================