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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 ffff888012c002fe by task syz-executor.2/5480

CPU: 1 PID: 5480 Comm: syz-executor.2 Not tainted 5.5.0-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:639
 __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:747 [inline]
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl+0x113/0x190 fs/ioctl.c:754
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:754
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b349
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:00007f8dd9c67c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8dd9c686d4 RCX: 000000000045b349
RDX: 00000000200001c0 RSI: 000000000000541c RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000056f R14: 00000000004c6b33 R15: 000000000075bf2c

Allocated by task 5358:
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:513
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x254/0x340 mm/slab.c:3665
 kmalloc_array include/linux/slab.h:598 [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:747 [inline]
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl+0x113/0x190 fs/ioctl.c:754
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:754
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5602:
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:335 [inline]
 __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:474
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483
 __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:747 [inline]
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl+0x113/0x190 fs/ioctl.c:754
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:754
 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 ffff888012c00000
 which belongs to the cache kmalloc-128k of size 131072
The buggy address is located 766 bytes inside of
 131072-byte region [ffff888012c00000, ffff888012c20000)
The buggy address belongs to the page:
page:ffffea00004b0000 refcount:1 mapcount:0 mapping:ffff8880aa4028c0 index:0x0 compound_mapcount: 0
raw: 00fffe0000010200 ffffea00010a2008 ffffea00004bf008 ffff8880aa4028c0
raw: 0000000000000000 ffff888012c00000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888012c00180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888012c00200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888012c00280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888012c00300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888012c00380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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