Kernel bug: possible deadlock in process_measurement (4)
Subsystem: lsm, integrity
Status: fixed

Crash report:
mmap: syz-executor369 (5231) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.
======================================================
WARNING: possible circular locking dependency detected
6.11.0-syzkaller-10045-g97d8894b6f4c #0 Not tainted
------------------------------------------------------
syz-executor369/5231 is trying to acquire lock:
ffff888072852370 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
ffff888072852370 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: process_measurement+0x439/0x1fb0 security/integrity/ima/ima_main.c:250

but task is already holding lock:
ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_remap_file_pages mm/mmap.c:1649 [inline]
ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_remap_file_pages+0x22d/0xa50 mm/mmap.c:1624

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
       down_read_killable+0xca/0xd30 kernel/locking/rwsem.c:1549
       mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:153
       get_mmap_lock_carefully mm/memory.c:6108 [inline]
       lock_mm_and_find_vma+0x29c/0x2f0 mm/memory.c:6159
       do_user_addr_fault arch/x86/mm/fault.c:1361 [inline]
       handle_page_fault arch/x86/mm/fault.c:1481 [inline]
       exc_page_fault+0x1bf/0x8c0 arch/x86/mm/fault.c:1539
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
       fault_in_readable+0x108/0x2b0 mm/gup.c:2227
       fault_in_iov_iter_readable+0x229/0x280 lib/iov_iter.c:94
       generic_perform_write+0x259/0x6d0 mm/filemap.c:4040
       shmem_file_write_iter+0xf9/0x120 mm/shmem.c:3221
       new_sync_write fs/read_write.c:590 [inline]
       vfs_write+0xa6d/0xc90 fs/read_write.c:683
       ksys_write+0x183/0x2b0 fs/read_write.c:736
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3158 [inline]
       check_prevs_add kernel/locking/lockdep.c:3277 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3901
       __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5199
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
       down_write+0x99/0x220 kernel/locking/rwsem.c:1579
       inode_lock include/linux/fs.h:815 [inline]
       process_measurement+0x439/0x1fb0 security/integrity/ima/ima_main.c:250
       ima_file_mmap+0x13d/0x2b0 security/integrity/ima/ima_main.c:455
       security_mmap_file+0x7e7/0xa40 security/security.c:2977
       __do_sys_remap_file_pages mm/mmap.c:1692 [inline]
       __se_sys_remap_file_pages+0x6e6/0xa50 mm/mmap.c:1624
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_lock);
                               lock(&sb->s_type->i_mutex_key#12);
                               lock(&mm->mmap_lock);
  lock(&sb->s_type->i_mutex_key#12);

 *** DEADLOCK ***

1 lock held by syz-executor369/5231:
 #0: ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
 #0: ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_remap_file_pages mm/mmap.c:1649 [inline]
 #0: ffff88807ac9a798 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_remap_file_pages+0x22d/0xa50 mm/mmap.c:1624

stack backtrace:
CPU: 1 UID: 0 PID: 5231 Comm: syz-executor369 Not tainted 6.11.0-syzkaller-10045-g97d8894b6f4c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2203
 check_prev_add kernel/locking/lockdep.c:3158 [inline]
 check_prevs_add kernel/locking/lockdep.c:3277 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3901
 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5199
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822
 down_write+0x99/0x220 kernel/locking/rwsem.c:1579
 inode_lock include/linux/fs.h:815 [inline]
 process_measurement+0x439/0x1fb0 security/integrity/ima/ima_main.c:250
 ima_file_mmap+0x13d/0x2b0 security/integrity/ima/ima_main.c:455
 security_mmap_file+0x7e7/0xa40 security/security.c:2977
 __do_sys_remap_file_pages mm/mmap.c:1692 [inline]
 __se_sys_remap_file_pages+0x6e6/0xa50 mm/mmap.c:1624
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff317efa919
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 18 00 00 90 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff317e94238 EFLAGS: 00000246 ORIG_RAX: 00000000000000d8
RAX: ffffffffffffffda RBX: 00007ff317f85318 RCX: 00007ff317efa919
RDX: 0000000000000000 RSI: 0000000000800000 RDI: 0000000020800000
RBP: 00007ff317f85310 R08: 0000000000010000 R09: 00007ff317e946c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff317f8531c
R13: 000000000000006e R14: 00007ffd154a5180 R15: 00007ffd154a5268
 </TASK>