Re: [syzbot] [sound?] BUG: sleeping function called from invalid context in vfree

[Takashi Iwai <tiwai@suse.de>]

On Mon, 25 Nov 2024 13:58:09 +0100,
Eric Dumazet wrote:
> 
> 
> On 11/25/24 1:54 PM, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    9f16d5e6f220 Merge tag 'for-linus' of git://git.kernel.org..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=154bc778580000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=47cc5fc1922531f
> > dashboard link: https://syzkaller.appspot.com/bug?extid=351f8764833934c68836
> > compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> > userspace arch: i386
> > 
> > Unfortunately, I don't have any reproducer for this issue yet.
> > 
> > Downloadable assets:
> > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-9f16d5e6.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/dddd5525a287/vmlinux-9f16d5e6.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/7c9e082ba50b/bzImage-9f16d5e6.xz
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+351f8764833934c68836@syzkaller.appspotmail.com
> > 
> > BUG: sleeping function called from invalid context at mm/vmalloc.c:3359
> > in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 6938, name: syz.1.230
> > preempt_count: 1, expected: 0
> > RCU nest depth: 0, expected: 0
> > 2 locks held by syz.1.230/6938:
> >   #0: ffff88804a2d2968 (&rmidi->open_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:201 [inline]
> >   #0: ffff88804a2d2968 (&rmidi->open_mutex){+.+.}-{4:4}, at: snd_rawmidi_output_params+0x51/0x1c0 sound/core/rawmidi.c:748
> >   #1: ffff888045e5ed48 (&substream->lock){....}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:376 [inline]
> >   #1: ffff888045e5ed48 (&substream->lock){....}-{3:3}, at: class_spinlock_irq_constructor include/linux/spinlock.h:565 [inline]
> >   #1: ffff888045e5ed48 (&substream->lock){....}-{3:3}, at: resize_runtime_buffer+0x243/0x530 sound/core/rawmidi.c:727
> > irq event stamp: 1218
> > hardirqs last  enabled at (1217): [<ffffffff8b189e32>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
> > hardirqs last  enabled at (1217): [<ffffffff8b189e32>] _raw_spin_unlock_irqrestore+0x52/0x80 kernel/locking/spinlock.c:194
> > hardirqs last disabled at (1218): [<ffffffff8b189ad5>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline]
> > hardirqs last disabled at (1218): [<ffffffff8b189ad5>] _raw_spin_lock_irq+0x45/0x50 kernel/locking/spinlock.c:170
> > softirqs last  enabled at (0): [<ffffffff814e57ac>] copy_process+0x1e9c/0x6f20 kernel/fork.c:2321
> > softirqs last disabled at (0): [<0000000000000000>] 0x0
> > Preemption disabled at:
> > [<0000000000000000>] 0x0
> > CPU: 1 UID: 0 PID: 6938 Comm: syz.1.230 Not tainted 6.12.0-syzkaller-09073-g9f16d5e6f220 #0
> > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> > Call Trace:
> >   <TASK>
> >   __dump_stack lib/dump_stack.c:94 [inline]
> >   dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
> >   __might_resched+0x3c0/0x5e0 kernel/sched/core.c:8758
> >   vfree+0x75/0x890 mm/vmalloc.c:3359
> >   kvfree+0x33/0x50 mm/util.c:699
> >   resize_runtime_buffer+0x3a7/0x530 sound/core/rawmidi.c:736
> >   snd_rawmidi_output_params+0xeb/0x1c0 sound/core/rawmidi.c:751
> >   snd_rawmidi_ioctl_params_compat sound/core/rawmidi_compat.c:37 [inline]
> >   snd_rawmidi_ioctl_compat+0x3ac/0x3e0 sound/core/rawmidi_compat.c:120
> >   __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004
> >   do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
> >   __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
> >   do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
> >   entry_SYSENTER_compat_after_hwframe+0x84/0x8e
> > RIP: 0023:0xf7f01579
> > Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> > RSP: 002b:00000000f506555c EFLAGS: 00000296 ORIG_RAX: 0000000000000036
> > RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 00000000c0205710
> > RDX: 0000000020000100 RSI: 0000000000000000 RDI: 0000000000000000
> > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
> > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> >   </TASK>
> > ----------------
> > Code disassembly (best guess), 2 bytes skipped:
> >     0:	10 06                	adc    %al,(%rsi)
> >     2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
> >     6:	10 07                	adc    %al,(%rdi)
> >     8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
> >     c:	10 08                	adc    %cl,(%rax)
> >     e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
> >    1e:	00 51 52             	add    %dl,0x52(%rcx)
> >    21:	55                   	push   %rbp
> >    22:	89 e5                	mov    %esp,%ebp
> >    24:	0f 34                	sysenter
> >    26:	cd 80                	int    $0x80
> > * 28:	5d                   	pop    %rbp <-- trapping instruction
> >    29:	5a                   	pop    %rdx
> >    2a:	59                   	pop    %rcx
> >    2b:	c3                   	ret
> >    2c:	90                   	nop
> >    2d:	90                   	nop
> >    2e:	90                   	nop
> >    2f:	90                   	nop
> >    30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
> >    37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
> > 
> > 
> > ---
> > This report is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@googlegroups.com.
> > 
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > 
> > If the report is already addressed, let syzbot know by replying with:
> > #syz fix: exact-commit-title
> > 
> > If you want to overwrite report's subsystems, reply with:
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> > (See the list of subsystem names on the web dashboard)
> > 
> > If the report is a duplicate of another one, reply with:
> > #syz dup: exact-subject-of-another-report
> > 
> > If you want to undo deduplication, reply with:
> > #syz undup
> 
> 
> Bug added in
> 
> commit 84bb065b316e8367e14a8824a8f4d21056b10c53
> Author: Takashi Iwai <tiwai@suse.de>
> Date:   Tue Feb 27 09:52:51 2024 +0100
> 
>   ALSA: rawmidi: Use guard() for locking
> 
>   We can simplify the code gracefully with new guard() macro and co for
>   automatic cleanup of locks.
> 
>   There are a few remaining explicit mutex and spinlock calls, and those
>   are the places where the temporary unlock/relocking happens -- which
>   guard() doens't cover well yet.
> 
>   Only the code refactoring, and no functional changes.
> 
>   Signed-off-by: Takashi Iwai <tiwai@suse.de>
>   Link:https://lore.kernel.org/r/20240227085306.9764-10-tiwai@suse.de
> <https://lore.kernel.org/r/20240227085306.9764-10-tiwai@suse.de>

Hmm, through a quick glance, I don't see anything breaking there.

Could you tell me which code path introduced the spinlock held during
kvzalloc() call in resize_runtime_buffer() in sound/core/rawmidi.c by
this commit...?


thanks,

Takashi