Re: [syzbot] [mm?] kernel BUG in __page_table_check_zero (2)

[Alan Stern]

On Mon, Nov 04, 2024 at 08:00:07PM -0800, Andrew Morton wrote:
> On Wed, 30 Oct 2024 21:54:22 -0700 syzbot <syzbot+ccc0e1cfdb72b664f0d8@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> 
> > Hello,
> > 
> > syzbot found the following issue on:
> 
> Thanks.  I'm suspecting some USB issue - fault injection was used to
> trigger a memory allocation failure and dec_usb_memory_use_count() ended
> up freeing an in-use page.  Could USB folks please have a look?

Andrew, I'm not sure what to look for.  Can you read through 
usbdev_mmap() in drivers/usb/core/devio.c, along with the four short 
routines preceding it, and let us know if anything seems obviously 
wrong?

Alan Stern

> > HEAD commit:    850925a8133c Merge tag '9p-for-6.12-rc5' of https://github..
> > git tree:       upstream
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1346c940580000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=309bb816d40abc28
> > dashboard link: https://syzkaller.appspot.com/bug?extid=ccc0e1cfdb72b664f0d8
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=158ab65f980000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=120e6a87980000
> > 
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/da8019730dec/disk-850925a8.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/b1ee80babbbc/vmlinux-850925a8.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/462580e2ad54/bzImage-850925a8.xz
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+ccc0e1cfdb72b664f0d8@xxxxxxxxxxxxxxxxxxxxxxxxx
> > 
> > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 1a 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007ffede422258 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
> > RAX: ffffffffffffffda RBX: 00007ffede422280 RCX: 00007f69e1b3c569
> > RDX: 0000000002000005 RSI: 0000000000003000 RDI: 000000002001a000
> > RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000080000000
> > R10: 0000000000011012 R11: 0000000000000246 R12: 00007ffede42227c
> > R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
> >  </TASK>
> > ------------[ cut here ]------------
> > kernel BUG at mm/page_table_check.c:157!
> > Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
> > CPU: 1 UID: 0 PID: 5850 Comm: syz-executor279 Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> > RIP: 0010:__page_table_check_zero+0x274/0x350 mm/page_table_check.c:157
> > Code: c1 0f 8c 39 fe ff ff 48 89 df e8 87 28 f3 ff e9 2c fe ff ff e8 dd 6a 89 ff 90 0f 0b e8 d5 6a 89 ff 90 0f 0b e8 cd 6a 89 ff 90 <0f> 0b f3 0f 1e fa 4c 89 f6 48 81 e6 ff 0f 00 00 31 ff e8 95 6f 89
> > RSP: 0018:ffffc900046bf6d8 EFLAGS: 00010293
> > RAX: ffffffff820b7fa3 RBX: dffffc0000000000 RCX: ffff88802fc13c00
> > RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88801e97380c
> > RBP: ffff88801e97380c R08: ffff88801e97380f R09: 1ffff11003d2e701
> > R10: dffffc0000000000 R11: ffffed1003d2e702 R12: ffff88801e9737c0
> > R13: 1ffffffff34887b4 R14: 0000000000000002 R15: 0000000000000000
> > FS:  0000555570714380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007f69e1b92385 CR3: 0000000073ae6000 CR4: 0000000000350ef0
> > Call Trace:
> >  <TASK>
> >  page_table_check_free include/linux/page_table_check.h:41 [inline]
> >  free_pages_prepare mm/page_alloc.c:1109 [inline]
> >  free_unref_page+0xd0f/0xf20 mm/page_alloc.c:2638
> >  dec_usb_memory_use_count+0x259/0x350 drivers/usb/core/devio.c:198
> >  mmap_region+0x2180/0x2a30 mm/mmap.c:1574
> >  do_mmap+0x8f0/0x1000 mm/mmap.c:496
> >  vm_mmap_pgoff+0x1dd/0x3d0 mm/util.c:588
> >  ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:542
> >  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> >  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> >  entry_SYSCALL_64_after_hwframe+0x77/0x7f