Re: [syzbot] KASAN: vmalloc-out-of-bounds Read in kvm_dev_ioctl

[Paolo Bonzini]

On 8/17/22 16:30, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    7ebfc85e2cd7 Merge tag 'net-6.0-rc1' of git://git.kernel.o..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10b66b6b080000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c15de4ee7650fb42
> dashboard link: https://syzkaller.appspot.com/bug?extid=8d24abd02cd4eb911bbd
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+8d24abd02cd4eb911bbd@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: vmalloc-out-of-bounds in __list_add_valid+0x93/0xb0 lib/list_debug.c:27
> Read of size 8 at addr ffffc90006b7a348 by task syz-executor.4/20901
>
> CPU: 1 PID: 20901 Comm: syz-executor.4 Not tainted 5.19.0-syzkaller-13930-g7ebfc85e2cd7 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
> Call Trace:
>   <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>   print_address_description mm/kasan/report.c:317 [inline]
>   print_report.cold+0x59/0x6e9 mm/kasan/report.c:433
>   kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
>   __list_add_valid+0x93/0xb0 lib/list_debug.c:27
>   __list_add include/linux/list.h:69 [inline]
>   list_add include/linux/list.h:88 [inline]
>   kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1219 [inline]
>   kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:4910 [inline]
>   kvm_dev_ioctl+0xf44/0x1ce0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4957
>   vfs_ioctl fs/ioctl.c:51 [inline]
>   __do_sys_ioctl fs/ioctl.c:870 [inline]
>   __se_sys_ioctl fs/ioctl.c:856 [inline]
>   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7fb1fba89279
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fb1fcc1e168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007fb1fbb9bf80 RCX: 00007fb1fba89279
> RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000004
> RBP: 00007fb1fbae3189 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffea48aadbf R14: 00007fb1fcc1e300 R15: 0000000000022000
>   </TASK>
>
> Memory state around the buggy address:
>   ffffc90006b7a200: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>   ffffc90006b7a280: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > ffffc90006b7a300: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>                                                ^
>   ffffc90006b7a380: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>   ffffc90006b7a400: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ==================================================================
>
>
> ---
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> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
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#syz dup: BUG: unable to handle kernel paging request in 
kvm_arch_hardware_enable