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References: <6744737b.050a0220.1cc393.007e.GAE@google.com> <874j3vzbbd.wl-tiwai@suse.de> Content-Language: en-US From: Eric Dumazet In-Reply-To: <874j3vzbbd.wl-tiwai@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 11/25/24 2:34 PM, Takashi Iwai wrote: > 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): [] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline] >>> hardirqs last enabled at (1217): [] _raw_spin_unlock_irqrestore+0x52/0x80 kernel/locking/spinlock.c:194 >>> hardirqs last disabled at (1218): [] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline] >>> hardirqs last disabled at (1218): [] _raw_spin_lock_irq+0x45/0x50 kernel/locking/spinlock.c:170 >>> softirqs last enabled at (0): [] 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: >>> >>> __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 >>> >>> ---------------- >>> 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: >>> #syz set subsystems: new-subsystem >>> (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 >> 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 >>   Link: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...? @@ -744,9 +724,8 @@ static int resize_runtime_buffer(struct snd_rawmidi_substream *substream,          newbuf = kvzalloc(params->buffer_size, GFP_KERNEL);          if (!newbuf)              return -ENOMEM; -        spin_lock_irq(&substream->lock); +        guard(spinlock_irq)(&substream->lock);          if (runtime->buffer_ref) { -            spin_unlock_irq(&substream->lock);              kvfree(newbuf);              return -EBUSY;          } @@ -754,7 +733,6 @@ static int resize_runtime_buffer(struct snd_rawmidi_substream *substream,          runtime->buffer = newbuf;          runtime->buffer_size = params->buffer_size;          __reset_runtime_ptrs(runtime, is_input); -        spin_unlock_irq(&substream->lock);          kvfree(oldbuf);      }      runtime->avail_min = params->avail_min; You can see that after your patch, kvfree() is called while guard(spinlock_irq)(&substream->lock); is still holding the lock.