Messages in this thread | | | Date | Mon, 24 Feb 2020 01:18:14 -0800 | Subject | KASAN: use-after-free Read in vt_do_kdgkb_ioctl | From | syzbot <> |
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Hello,
syzbot found the following crash on:
HEAD commit: 54dedb5b Merge tag 'for-linus-5.6-rc3-tag' of git://git.ke.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=100403d9e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=3b8906eb6a7d6028 dashboard link: https://syzkaller.appspot.com/bug?extid=a58bfd517766aef83043 compiler: gcc (GCC) 9.0.0 20181231 (experimental)
Unfortunately, I don't have any reproducer for this crash yet.
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+a58bfd517766aef83043@syzkaller.appspotmail.com
================================================================== BUG: KASAN: use-after-free in vt_do_kdgkb_ioctl+0xb24/0xb50 drivers/tty/vt/keyboard.c:2025 Read of size 1 at addr ffff8880a4a8c801 by task syz-executor.4/27890
CPU: 1 PID: 27890 Comm: syz-executor.4 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+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:641 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:132 vt_do_kdgkb_ioctl+0xb24/0xb50 drivers/tty/vt/keyboard.c:2025 vt_ioctl+0x47e/0x26c0 drivers/tty/vt/vt_ioctl.c:549 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c429 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:00007f0f2868cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f0f2868d6d4 RCX: 000000000045c429 RDX: 0000000020000200 RSI: 0000000000004b48 RDI: 0000000000000003 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000041a R14: 00000000004c676d R15: 000000000076bf2c
Allocated by task 1548: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x163/0x770 mm/slab.c:3665 kmalloc include/linux/slab.h:560 [inline] vt_do_kdgkb_ioctl+0x3d1/0xb50 drivers/tty/vt/keyboard.c:2078 vt_ioctl+0x47e/0x26c0 drivers/tty/vt/vt_ioctl.c:549 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 27892: 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:337 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 vt_do_kdgkb_ioctl+0x5b4/0xb50 drivers/tty/vt/keyboard.c:2104 vt_ioctl+0x47e/0x26c0 drivers/tty/vt/vt_ioctl.c:549 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x123/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770 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 ffff8880a4a8c800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 1 bytes inside of 1024-byte region [ffff8880a4a8c800, ffff8880a4a8cc00) The buggy address belongs to the page: page:ffffea000292a300 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00026aa6c8 ffffea000210b1c8 ffff8880aa400c40 raw: 0000000000000000 ffff8880a4a8c000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8880a4a8c700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a4a8c780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880a4a8c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a4a8c880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a4a8c900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
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