================================================================== BUG: KASAN: use-after-free in n_tty_receive_buf_fast drivers/tty/n_tty.c:1602 [inline] BUG: KASAN: use-after-free in __receive_buf drivers/tty/n_tty.c:1644 [inline] BUG: KASAN: use-after-free in n_tty_receive_buf_common+0x1f95/0x30b0 drivers/tty/n_tty.c:1742 Read of size 1 at addr ffff888096c4d0fb by task syz-executor.1/19953 CPU: 0 PID: 19953 Comm: syz-executor.1 Not tainted 5.6.0-rc2-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+0x1fb/0x318 lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x149/0x1c0 mm/kasan/report.c:506 kasan_report+0x26/0x50 mm/kasan/common.c:641 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:132 n_tty_receive_buf_fast drivers/tty/n_tty.c:1602 [inline] __receive_buf drivers/tty/n_tty.c:1644 [inline] n_tty_receive_buf_common+0x1f95/0x30b0 drivers/tty/n_tty.c:1742 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1777 tty_ldisc_receive_buf+0x9f/0x170 drivers/tty/tty_buffer.c:461 paste_selection+0x2ef/0x400 drivers/tty/vt/selection.c:372 tioclinux+0x121/0x530 drivers/tty/vt/vt.c:3044 vt_ioctl+0x3f1/0x3a70 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xee6/0x15c0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:763 [inline] __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:770 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:770 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c449 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:00007fae1604cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fae1604d6d4 RCX: 000000000045c449 RDX: 0000000020000100 RSI: 000000000000541c RDI: 0000000000000003 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000574 R14: 00000000004c7c6f R15: 000000000076bf2c Allocated by task 19941: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:515 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x254/0x340 mm/slab.c:3665 kmalloc_array include/linux/slab.h:597 [inline] set_selection_kernel+0xea3/0x1880 drivers/tty/vt/selection.c:305 set_selection_user+0x63/0x80 drivers/tty/vt/selection.c:177 tioclinux+0x103/0x530 drivers/tty/vt/vt.c:3039 vt_ioctl+0x3f1/0x3a70 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xee6/0x15c0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:763 [inline] __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:770 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:770 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 19952: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10d/0x220 mm/slab.c:3757 set_selection_kernel+0xec8/0x1880 drivers/tty/vt/selection.c:312 set_selection_user+0x63/0x80 drivers/tty/vt/selection.c:177 tioclinux+0x103/0x530 drivers/tty/vt/vt.c:3039 vt_ioctl+0x3f1/0x3a70 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xee6/0x15c0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:763 [inline] __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:770 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:770 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888096c4d000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 251 bytes inside of 2048-byte region [ffff888096c4d000, ffff888096c4d800) The buggy address belongs to the page: page:ffffea00025b1340 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0002686888 ffffea00028ba408 ffff8880aa400e00 raw: 0000000000000000 ffff888096c4d000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888096c4cf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888096c4d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888096c4d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888096c4d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888096c4d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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