syzbot


KASAN: global-out-of-bounds Read in fbcon_resize

Status: fixed on 2020/10/10 01:52
Reported-by: syzbot+b38b1ef6edf0c74a8d97@syzkaller.appspotmail.com
Fix commit: ec0972adecb3 fbcon: Fix user font detection test at fbcon_resize().
First crash: 772d, last: 740d

Cause bisection: failed (bisect log)
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: global-out-of-bounds Read in fbcon_resize C done 529 709d 757d 1/1 fixed on 2020/11/21 10:42
linux-4.19 KASAN: global-out-of-bounds Read in fbcon_resize C done 286 737d 757d 1/1 fixed on 2020/10/23 18:53
Patch testing requests:
Created Duration User Patch Repo Result
2020/09/10 11:30 17m penguin-kernel@i-love.sakura.ne.jp patch upstream OK
2020/09/10 10:25 10m penguin-kernel@i-love.sakura.ne.jp patch upstream report log
2020/09/10 07:18 10m penguin-kernel@i-love.sakura.ne.jp patch upstream report log
2020/09/10 00:54 17m penguin-kernel@i-love.sakura.ne.jp patch upstream OK
2020/09/10 00:05 10m penguin-kernel@i-love.sakura.ne.jp patch upstream report log
2020/08/20 06:20 16m anmol.karan123@gmail.com upstream OK

Sample crash report:
==================================================================
BUG: KASAN: global-out-of-bounds in fbcon_resize+0x781/0x810 drivers/video/fbdev/core/fbcon.c:2206
Read of size 4 at addr ffffffff8896c2d8 by task syz-executor747/6851

CPU: 1 PID: 6851 Comm: syz-executor747 Not tainted 5.9.0-rc4-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+0x198/0x1fd lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0x5/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 fbcon_resize+0x781/0x810 drivers/video/fbdev/core/fbcon.c:2206
 resize_screen drivers/tty/vt/vt.c:1175 [inline]
 vc_do_resize+0x535/0x1150 drivers/tty/vt/vt.c:1246
 vt_ioctl+0x11d2/0x2cc0 drivers/tty/vt/vt_ioctl.c:1025
 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x445959
Code: e8 fc b8 02 00 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 0b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff020829db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dac38 RCX: 0000000000445959
RDX: 0000000020001740 RSI: 0000000000005609 RDI: 0000000000000006
RBP: 00000000006dac30 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac3c
R13: 00007fff73df80ff R14: 00007ff02082a9c0 R15: 20c49ba5e353f7cf

The buggy address belongs to the variable:
 font_vga_8x16+0x58/0x60

Memory state around the buggy address:
 ffffffff8896c180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff8896c200: 00 00 00 00 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
>ffffffff8896c280: 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
                                                    ^
 ffffffff8896c300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff8896c380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (673):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2020/09/09 13:54 upstream 34d4ddd359db 0ea7a887 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2020/09/09 03:28 upstream 612ab8ad6414 abf9ba4f .config log report syz C
ci-upstream-kasan-gce-root 2020/09/08 01:38 upstream f4d51dffc6c0 abf9ba4f .config log report syz C
ci-upstream-linux-next-kasan-gce-root 2020/08/22 23:57 linux-next 494d311a82bb 1da71ab0 .config log report syz C
ci-upstream-linux-next-kasan-gce-root 2020/08/20 01:56 linux-next 8eb858df0a5f 94b45706 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2020/09/09 08:05 upstream 612ab8ad6414 abf9ba4f .config log report syz
ci-upstream-kasan-gce-root 2020/09/07 20:39 upstream f4d51dffc6c0 abf9ba4f .config log report syz
ci-upstream-kasan-gce-root 2020/09/21 03:50 upstream 325d0eab4f31 9564d2e9 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/21 02:40 upstream 325d0eab4f31 9564d2e9 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/21 01:24 upstream 325d0eab4f31 9564d2e9 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/20 14:34 upstream 325d0eab4f31 9564d2e9 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/20 12:03 upstream 325d0eab4f31 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/20 10:24 upstream 325d0eab4f31 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/20 08:38 upstream 325d0eab4f31 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/20 07:24 upstream 325d0eab4f31 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/20 07:20 upstream 325d0eab4f31 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/20 04:08 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/20 02:44 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/20 01:23 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/19 20:37 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/19 19:31 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/19 17:40 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/19 16:31 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/19 15:53 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/19 12:37 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/19 09:57 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/19 08:01 upstream eb5f95f1593f 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/19 06:28 upstream 10b82d517648 53ce8104 .config log report info
ci-upstream-kasan-gce-root 2020/09/18 20:05 upstream 10b82d517648 53ce8104 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 17:50 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 15:54 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 14:45 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-root 2020/09/18 12:38 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-root 2020/09/18 10:58 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 09:45 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 08:49 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 07:48 upstream 4cbffc461ec9 38962c8b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 05:50 upstream 4cbffc461ec9 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 04:46 upstream 4cbffc461ec9 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 02:38 upstream 4cbffc461ec9 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/18 00:06 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 23:22 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 22:18 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 21:07 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 19:50 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 18:48 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 17:50 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 15:35 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 13:22 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 11:08 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-root 2020/09/17 08:36 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 07:11 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/17 05:09 upstream 5925fa68fe82 8247808b .config log report info
ci-upstream-kasan-gce-root 2020/09/17 04:06 upstream 5925fa68fe82 8247808b .config log report info
ci-qemu-upstream-386 2020/09/07 11:59 upstream f4d51dffc6c0 abf9ba4f .config log report
ci-upstream-linux-next-kasan-gce-root 2020/09/17 12:17 linux-next 5fa35f247b56 8247808b .config log report info
ci-upstream-linux-next-kasan-gce-root 2020/09/17 09:39 linux-next 5fa35f247b56 8247808b .config log report info
ci-upstream-linux-next-kasan-gce-root 2020/09/17 07:31 linux-next 5fa35f247b56 8247808b .config log report info
ci-upstream-linux-next-kasan-gce-root 2020/08/20 01:11 linux-next 8eb858df0a5f 94b45706 .config log report
* Struck through repros no longer work on HEAD.