From: syzbot <syzbot+6884a790570df1022b2d@syzkaller.appspotmail.com>
To: arnd@arndb.de, gregkh@linuxfoundation.org, jrdr.linux@gmail.com,
keescook@chromium.org, kstewart@linuxfoundation.org,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
mawilcox@microsoft.com, pombredanne@nexb.com,
syzkaller-bugs@googlegroups.com, tglx@linutronix.de,
viro@zeniv.linux.org.uk, zaitcev@redhat.com
Subject: Re: possible deadlock in __might_fault (3)
Date: Sat, 01 Sep 2018 00:49:02 -0700 [thread overview]
Message-ID: <000000000000a99aef0574ca8a7b@google.com> (raw)
In-Reply-To: <00000000000008e7340574ab473a@google.com>
syzbot has found a reproducer for the following crash on:
HEAD commit: a880148cb2af Add linux-next specific files for 20180831
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16b6013e400000
kernel config: https://syzkaller.appspot.com/x/.config?x=a059d319ef7d83f6
dashboard link: https://syzkaller.appspot.com/bug?extid=6884a790570df1022b2d
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10ecaa46400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f60151400000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6884a790570df1022b2d@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
4.19.0-rc1-next-20180831+ #53 Not tainted
------------------------------------------------------
syz-executor560/5342 is trying to acquire lock:
00000000d0c295b6 (&mm->mmap_sem){++++}, at: __might_fault+0xfb/0x1e0
mm/memory.c:4577
but task is already holding lock:
000000000e449f78 (&rp->fetch_lock){+.+.}, at: mon_bin_get_event+0x3f/0x460
drivers/usb/mon/mon_bin.c:747
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&rp->fetch_lock){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0x171/0x1700 kernel/locking/mutex.c:1073
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
mon_bin_vma_fault+0xdc/0x4a0 drivers/usb/mon/mon_bin.c:1237
__do_fault+0xee/0x450 mm/memory.c:3240
do_cow_fault mm/memory.c:3681 [inline]
do_fault mm/memory.c:3754 [inline]
handle_pte_fault mm/memory.c:3983 [inline]
__handle_mm_fault+0x13c6/0x4350 mm/memory.c:4107
handle_mm_fault+0x53e/0xc80 mm/memory.c:4144
faultin_page mm/gup.c:518 [inline]
__get_user_pages+0x823/0x1b50 mm/gup.c:718
populate_vma_page_range+0x2db/0x3d0 mm/gup.c:1222
__mm_populate+0x286/0x4d0 mm/gup.c:1270
mm_populate include/linux/mm.h:2307 [inline]
vm_mmap_pgoff+0x27f/0x2c0 mm/util.c:362
ksys_mmap_pgoff+0x4da/0x660 mm/mmap.c:1585
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
__x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&mm->mmap_sem){++++}:
lock_acquire+0x1e4/0x4f0 kernel/locking/lockdep.c:3901
__might_fault+0x155/0x1e0 mm/memory.c:4578
_copy_to_user+0x30/0x110 lib/usercopy.c:25
copy_to_user include/linux/uaccess.h:155 [inline]
mon_bin_get_event+0x116/0x460 drivers/usb/mon/mon_bin.c:756
mon_bin_ioctl+0x459/0xe80 drivers/usb/mon/mon_bin.c:1068
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
__do_sys_ioctl fs/ioctl.c:709 [inline]
__se_sys_ioctl fs/ioctl.c:707 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&rp->fetch_lock);
lock(&mm->mmap_sem);
lock(&rp->fetch_lock);
lock(&mm->mmap_sem);
*** DEADLOCK ***
1 lock held by syz-executor560/5342:
#0: 000000000e449f78 (&rp->fetch_lock){+.+.}, at:
mon_bin_get_event+0x3f/0x460 drivers/usb/mon/mon_bin.c:747
stack backtrace:
CPU: 0 PID: 5342 Comm: syz-executor560 Not tainted
4.19.0-rc1-next-20180831+ #53
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+0x1c9/0x2b4 lib/dump_stack.c:113
print_circular_bug.isra.34.cold.55+0x1bd/0x27d
kernel/locking/lockdep.c:1222
check_prev_add kernel/locking/lockdep.c:1862 [inline]
check_prevs_add kernel/locking/lockdep.c:1975 [inline]
validate_chain kernel/locking/lockdep.c:2416 [inline]
__lock_acquire+0x3449/0x5020 kernel/locking/lockdep.c:3412
lock_acquire+0x1e4/0x4f0 kernel/locking/lockdep.c:3901
__might_fault+0x155/0x1e0 mm/memory.c:4578
_copy_to_user+0x30/0x110 lib/usercopy.c:25
copy_to_user include/linux/uaccess.h:155 [inline]
mon_bin_get_event+0x116/0x460 drivers/usb/mon/mon_bin.c:756
mon_bin_ioctl+0x459/0xe80 drivers/usb/mon/mon_bin.c:1068
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
__do_sys_ioctl fs/ioctl.c:709 [inline]
__se_sys_ioctl fs/ioctl.c:707 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44a139
Code: e8 6c b4 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 4b cd fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fa6f2498da8 EFLAGS: 00000293 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc68 RCX: 000000000044a139
RDX: 0000000020000000 RSI: 000000004018920a RDI: 0000000000000005
RBP: 00000000006dbc60 R08: 00007fa6f2499700 R09: 0000000000000000
R10: 00007fa6f2499700 R11: 0000000000000293 R12: 00000000006dbc6c
R13: 6273752f7665642f R14: 7375622f7665642f R15: 00000000006dbd4c
prev parent reply other threads:[~2018-09-01 7:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-30 18:31 possible deadlock in __might_fault (3) syzbot
2018-09-01 7:49 ` syzbot [this message]
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