possible deadlock in __might_fault (3)

From: syzbot
Date: Thu Aug 30 2018 - 14:31:09 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 58c3f14f86c9 Merge tag 'riscv-for-linus-4.19-rc2' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13795092400000
kernel config: https://syzkaller.appspot.com/x/.config?x=531a917630d2a492
dashboard link: https://syzkaller.appspot.com/bug?extid=6884a790570df1022b2d
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
userspace arch: i386

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6884a790570df1022b2d@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
4.19.0-rc1+ #118 Not tainted
------------------------------------------------------
syz-executor7/25985 is trying to acquire lock:
00000000bd99782f (&mm->mmap_sem){++++}, at: __might_fault+0xfb/0x1e0 mm/memory.c:4577

but task is already holding lock:
00000000a8e804bc (&rp->fetch_lock){+.+.}, at: mon_bin_fetch+0x37/0x340 drivers/usb/mon/mon_bin.c:909

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_read_fault mm/memory.c:3652 [inline]
do_fault mm/memory.c:3752 [inline]
handle_pte_fault mm/memory.c:3983 [inline]
__handle_mm_fault+0x2b4a/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_pgoff mm/mmap.c:1596 [inline]
__se_sys_mmap_pgoff mm/mmap.c:1592 [inline]
__ia32_sys_mmap_pgoff+0xdd/0x1a0 mm/mmap.c:1592
do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
do_fast_syscall_32+0x34d/0xfb2 arch/x86/entry/common.c:397
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

-> #0 (&mm->mmap_sem){++++}:
lock_acquire+0x1e4/0x4f0 kernel/locking/lockdep.c:3901
__might_fault+0x155/0x1e0 mm/memory.c:4578
mon_bin_fetch+0x26f/0x340 drivers/usb/mon/mon_bin.c:928
mon_bin_compat_ioctl+0x232/0x560 drivers/usb/mon/mon_bin.c:1170
__do_compat_sys_ioctl fs/compat_ioctl.c:1419 [inline]
__se_compat_sys_ioctl fs/compat_ioctl.c:1365 [inline]
__ia32_compat_sys_ioctl+0x221/0x640 fs/compat_ioctl.c:1365
do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
do_fast_syscall_32+0x34d/0xfb2 arch/x86/entry/common.c:397
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

other info that might help us debug this:

Possible unsafe locking scenario:

TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters.
CPU0 CPU1
---- ----
lock(&rp->fetch_lock);
lock(&mm->mmap_sem);
lock(&rp->fetch_lock);
lock(&mm->mmap_sem);
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters.

*** DEADLOCK ***

1 lock held by syz-executor7/25985:
#0: 00000000a8e804bc (&rp->fetch_lock){+.+.}, at: mon_bin_fetch+0x37/0x340 drivers/usb/mon/mon_bin.c:909

stack backtrace:
CPU: 1 PID: 25985 Comm: syz-executor7 Not tainted 4.19.0-rc1+ #118
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
mon_bin_fetch+0x26f/0x340 drivers/usb/mon/mon_bin.c:928
mon_bin_compat_ioctl+0x232/0x560 drivers/usb/mon/mon_bin.c:1170
__do_compat_sys_ioctl fs/compat_ioctl.c:1419 [inline]
__se_compat_sys_ioctl fs/compat_ioctl.c:1365 [inline]
__ia32_compat_sys_ioctl+0x221/0x640 fs/compat_ioctl.c:1365
do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
do_fast_syscall_32+0x34d/0xfb2 arch/x86/entry/common.c:397
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f2aca9
Code: 55 08 8b 88 64 cd ff ff 8b 98 68 cd ff ff 89 c8 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 1c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5f260cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000c00c9207
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters.
RDX: 0000000020000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
device bridge0 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge0: port 1(bridge_slave_0) entered disabled state

---
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Previous message: Arnaldo Carvalho de Melo: "Re: [PATCH] perf trace beautify: Beautify flags of mount(2) and umount(2)."
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