================================================================== BUG: KASAN: use-after-free in n_tty_check_throttle drivers/tty/n_tty.c:264 [inline] BUG: KASAN: use-after-free in n_tty_receive_buf_common+0x26a4/0x2ab0 drivers/tty/n_tty.c:1759 Read of size 1 at addr ffff888095a5c2bb by task syz-executor.5/28571 CPU: 0 PID: 28571 Comm: syz-executor.5 Not tainted 4.19.100-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.cold+0x7c/0x20d mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 n_tty_check_throttle drivers/tty/n_tty.c:264 [inline] n_tty_receive_buf_common+0x26a4/0x2ab0 drivers/tty/n_tty.c:1759 n_tty_receive_buf2+0x34/0x40 drivers/tty/n_tty.c:1775 tty_ldisc_receive_buf+0xad/0x1c0 drivers/tty/tty_buffer.c:456 paste_selection+0x1ff/0x443 drivers/tty/vt/selection.c:359 tioclinux+0x133/0x470 drivers/tty/vt/vt.c:3019 vt_ioctl+0x19ab/0x2530 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0x7f3/0x1510 drivers/tty/tty_io.c:2669 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b399 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f97b84c4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f97b84c56d4 RCX: 000000000045b399 RDX: 0000000020000040 RSI: 000000000000541c RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000056c R14: 00000000004c6b4d R15: 000000000075bf2c Allocated by task 28539: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531 __do_kmalloc mm/slab.c:3727 [inline] __kmalloc+0x15d/0x750 mm/slab.c:3736 kmalloc_array include/linux/slab.h:637 [inline] set_selection+0x7e4/0x1370 drivers/tty/vt/selection.c:293 tioclinux+0x11c/0x470 drivers/tty/vt/vt.c:3015 vt_ioctl+0x19ab/0x2530 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0x7f3/0x1510 drivers/tty/tty_io.c:2669 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 28584: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kfree+0xcf/0x220 mm/slab.c:3822 set_selection+0x801/0x1370 drivers/tty/vt/selection.c:300 tioclinux+0x11c/0x470 drivers/tty/vt/vt.c:3015 vt_ioctl+0x19ab/0x2530 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0x7f3/0x1510 drivers/tty/tty_io.c:2669 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888095a5c1c0 which belongs to the cache kmalloc-4096 of size 4096 The buggy address is located 251 bytes inside of 4096-byte region [ffff888095a5c1c0, ffff888095a5d1c0) The buggy address belongs to the page: page:ffffea0002569700 count:1 mapcount:0 mapping:ffff88812c31cdc0 index:0x0 compound_mapcount: 0 flags: 0xfffe0000008100(slab|head) raw: 00fffe0000008100 ffffea00025b5d08 ffffea0001309608 ffff88812c31cdc0 raw: 0000000000000000 ffff888095a5c1c0 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888095a5c180: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff888095a5c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888095a5c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888095a5c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888095a5c380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================