syzbot


possible deadlock in __do_page_fault (2)

Status: closed as invalid on 2019/06/23 22:18
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+606e524a3ca9617cf8c0@syzkaller.appspotmail.com
First crash: 1847d, last: 1843d
Cause bisection: introduced by (bisect log) :
commit 69d61f577d147b396be0991b2ac6f65057f7d445
Author: Mimi Zohar <zohar@linux.ibm.com>
Date: Wed Apr 3 21:47:46 2019 +0000

  ima: verify mprotect change is consistent with mmap policy

Crash: possible deadlock in __do_page_fault (log)
Repro: syz .config
  
Discussions (1)
Title Replies (including bot) Last reply
possible deadlock in __do_page_fault (2) 1 (5) 2019/06/04 20:08
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 possible deadlock in __do_page_fault C 3356 1661d 1898d 0/1 public: reported C repro on 2019/04/11 00:00
android-49 possible deadlock in __do_page_fault C 801 1661d 1898d 0/3 public: reported C repro on 2019/04/11 08:44
upstream possible deadlock in __do_page_fault fs mm C 820 1933d 2100d 11/27 fixed on 2019/03/28 12:00

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.2.0-rc3-next-20190604 #8 Not tainted
------------------------------------------------------
syz-executor361/10886 is trying to acquire lock:
00000000c4471342 (&mm->mmap_sem#2){++++}, at: do_user_addr_fault arch/x86/mm/fault.c:1406 [inline]
00000000c4471342 (&mm->mmap_sem#2){++++}, at: __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1521

but task is already holding lock:
000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_trylock include/linux/fs.h:798 [inline]
000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: ext4_file_write_iter+0x246/0x1070 fs/ext4/file.c:232

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#10){+.+.}:
       down_write+0x38/0xa0 kernel/locking/rwsem.c:66
       inode_lock include/linux/fs.h:778 [inline]
       process_measurement+0x15ae/0x15e0 security/integrity/ima/ima_main.c:228
       ima_file_mmap+0x11a/0x130 security/integrity/ima/ima_main.c:370
       security_file_mprotect+0xd5/0x100 security/security.c:1426
       do_mprotect_pkey+0x537/0xa30 mm/mprotect.c:550
       __do_sys_mprotect mm/mprotect.c:582 [inline]
       __se_sys_mprotect mm/mprotect.c:579 [inline]
       __x64_sys_mprotect+0x78/0xb0 mm/mprotect.c:579
       do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&mm->mmap_sem#2){++++}:
       lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4300
       down_read+0x3f/0x1e0 kernel/locking/rwsem.c:24
       do_user_addr_fault arch/x86/mm/fault.c:1406 [inline]
       __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1521
       do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1552
       page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156
       fault_in_pages_readable include/linux/pagemap.h:600 [inline]
       iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:426
       generic_perform_write+0x186/0x520 mm/filemap.c:3197
       __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3336
       ext4_file_write_iter+0x332/0x1070 fs/ext4/file.c:266
       call_write_iter include/linux/fs.h:1870 [inline]
       new_sync_write+0x4d3/0x770 fs/read_write.c:483
       __vfs_write+0xe1/0x110 fs/read_write.c:496
       vfs_write+0x268/0x5d0 fs/read_write.c:558
       ksys_write+0x14f/0x290 fs/read_write.c:611
       __do_sys_write fs/read_write.c:623 [inline]
       __se_sys_write fs/read_write.c:620 [inline]
       __x64_sys_write+0x73/0xb0 fs/read_write.c:620
       do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sb->s_type->i_mutex_key#10);
                               lock(&mm->mmap_sem#2);
                               lock(&sb->s_type->i_mutex_key#10);
  lock(&mm->mmap_sem#2);

 *** DEADLOCK ***

3 locks held by syz-executor361/10886:
 #0: 00000000b8e64295 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801
 #1: 00000000e032805f (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2836 [inline]
 #1: 00000000e032805f (sb_writers#3){.+.+}, at: vfs_write+0x485/0x5d0 fs/read_write.c:557
 #2: 000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_trylock include/linux/fs.h:798 [inline]
 #2: 000000009878d2b3 (&sb->s_type->i_mutex_key#10){+.+.}, at: ext4_file_write_iter+0x246/0x1070 fs/ext4/file.c:232

stack backtrace:
CPU: 0 PID: 10886 Comm: syz-executor361 Not tainted 5.2.0-rc3-next-20190604 #8
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+0x172/0x1f0 lib/dump_stack.c:113
 print_circular_bug.cold+0x1cc/0x28f kernel/locking/lockdep.c:1566
 check_prev_add kernel/locking/lockdep.c:2311 [inline]
 check_prevs_add kernel/locking/lockdep.c:2419 [inline]
 validate_chain kernel/locking/lockdep.c:2801 [inline]
 __lock_acquire+0x3755/0x5490 kernel/locking/lockdep.c:3790
 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4300
 down_read+0x3f/0x1e0 kernel/locking/rwsem.c:24
 do_user_addr_fault arch/x86/mm/fault.c:1406 [inline]
 __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1521
 do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1552
 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156
RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:600 [inline]
RIP: 0010:iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:426
Code: 89 f6 41 88 57 e0 e8 b8 dd 3c fe 45 85 f6 74 c1 e9 70 fe ff ff e8 29 dc 3c fe 0f 1f 00 0f ae e8 44 89 f0 48 8b 8d 68 ff ff ff <8a> 11 89 c3 0f 1f 00 41 88 57 d0 31 ff 89 de e8 85 dd 3c fe 85 db
RSP: 0018:ffff88808ca6f918 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000200011ff
RDX: 0000000000000000 RSI: ffffffff83341b37 RDI: 0000000000000007
RBP: ffff88808ca6f9b8 R08: ffff88809be68000 R09: ffff88809be688f8
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001000
R13: 0000000000001000 R14: 0000000000000000 R15: ffff88808ca6f990
 generic_perform_write+0x186/0x520 mm/filemap.c:3197
 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3336
 ext4_file_write_iter+0x332/0x1070 fs/ext4/file.c:266
 call_write_iter include/linux/fs.h:1870 [inline]
 new_sync_write+0x4d3/0x770 fs/read_write.c:483
 __vfs_write+0xe1/0x110 fs/read_write.c:496
 vfs_write+0x268/0x5d0 fs/read_write.c:558
 ksys_write+0x14f/0x290 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:620
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446939
Code: e8 4c 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 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007effabbcdce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446939
RDX: 000000000007fe00 RSI: 0000000020000200 RDI: 0000000000000006
RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c
R13: 00007ffd5dd15ddf R14: 00007effabbce9c0 R15: 20c49ba5e353f7cf

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/06/04 20:06 linux-next 56b697c6c13b e41a20c5 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2019/06/03 15:14 linux-next 3c09c1950c84 63bf051f .config console log report syz ci-upstream-linux-next-kasan-gce-root
2019/06/05 06:26 linux-next 56b697c6c13b bfb4a51e .config console log report ci-upstream-linux-next-kasan-gce-root
2019/06/05 02:23 linux-next 56b697c6c13b bfb4a51e .config console log report ci-upstream-linux-next-kasan-gce-root
2019/06/04 10:13 linux-next 56b697c6c13b ce07a7ae .config console log report ci-upstream-linux-next-kasan-gce-root
2019/06/04 00:06 linux-next 3c09c1950c84 ce07a7ae .config console log report ci-upstream-linux-next-kasan-gce-root
2019/06/03 13:31 linux-next 3c09c1950c84 63bf051f .config console log report ci-upstream-linux-next-kasan-gce-root
2019/05/31 13:53 linux-next 3c09c1950c84 142ce681 .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.