[syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    684a64bf32b6 Merge tag 'nfs-for-6.12-1' of git://git.linux..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11d9299f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bd75e1a00004094f
dashboard link: https://syzkaller.appspot.com/bug?extid=a6456f6334aa19425886
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/72e96b8890d5/disk-684a64bf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/27bdd881ea38/vmlinux-684a64bf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/315166afeb3a/bzImage-684a64bf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a6456f6334aa19425886@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.11.0-syzkaller-10547-g684a64bf32b6 #0 Not tainted
------------------------------------------------------
syz.3.2933/22916 is trying to acquire lock:
ffff88807bf96a18 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
ffff88807bf96a18 (&mm->mmap_lock){++++}-{3:3}, at: upgrade_mmap_lock_carefully+0xb6/0x160 mm/memory.c:6132

but task is already holding lock:
ffff888078651ce8 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
ffff888078651ce8 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: shmem_file_write_iter+0x80/0x120 mm/shmem.c:3211

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}:
       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

-> #0 (&mm->mmap_lock){++++}-{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_killable+0xab/0x260 kernel/locking/rwsem.c:1590
       mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
       upgrade_mmap_lock_carefully+0xb6/0x160 mm/memory.c:6132
       lock_mm_and_find_vma+0x107/0x2f0 mm/memory.c:6185
       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+0x165/0x2b0
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz.3.2933/22916:
 #0: ffff8880391b2478 (&f->f_pos_lock){+.+.}-{3:3}, at: fdget_pos+0x24e/0x320 fs/file.c:1187
 #1: ffff888043608420 (sb_writers#5){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2931 [inline]
 #1: ffff888043608420 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0x224/0xc90 fs/read_write.c:679
 #2: ffff888078651ce8 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
 #2: ffff888078651ce8 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: shmem_file_write_iter+0x80/0x120 mm/shmem.c:3211

stack backtrace:
CPU: 1 UID: 0 PID: 22916 Comm: syz.3.2933 Not tainted 6.11.0-syzkaller-10547-g684a64bf32b6 #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_killable+0xab/0x260 kernel/locking/rwsem.c:1590
 mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
 upgrade_mmap_lock_carefully+0xb6/0x160 mm/memory.c:6132
 lock_mm_and_find_vma+0x107/0x2f0 mm/memory.c:6185
 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
RIP: 0010:fault_in_readable+0x165/0x2b0 mm/gup.c:2235
Code: b3 ff 4c 8d b3 ff 0f 00 00 48 89 d8 4d 01 e6 49 81 e6 00 f0 ff ff 49 39 c6 72 6b e8 95 cd b3 ff 4c 39 f3 74 6e 4c 89 64 24 10 <44> 8a 23 43 0f b6 04 2f 84 c0 75 18 44 88 64 24 40 48 81 c3 00 10
RSP: 0018:ffffc9000fa67a40 EFLAGS: 00050287
RAX: ffffffff81e0e7ab RBX: 0000000020001000 RCX: 0000000000040000
RDX: ffffc90004fa1000 RSI: 000000000000007d RDI: 000000000000007e
RBP: ffffc9000fa67af8 R08: ffffffff81e0e748 R09: ffffffff84b90999
R10: 0000000000000002 R11: ffff88805c679e00 R12: 000000000000fecc
R13: dffffc0000000000 R14: 0000000020010000 R15: 1ffff92001f4cf50
 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
RIP: 0033:0x7fde8757def9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fde86fff038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fde87735f80 RCX: 00007fde8757def9
RDX: 000000000000fecc RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00007fde875f0b76 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fde87735f80 R15: 00007fde8785fa28
 </TASK>
----------------
Code disassembly (best guess):
   0:	b3 ff                	mov    $0xff,%bl
   2:	4c 8d b3 ff 0f 00 00 	lea    0xfff(%rbx),%r14
   9:	48 89 d8             	mov    %rbx,%rax
   c:	4d 01 e6             	add    %r12,%r14
   f:	49 81 e6 00 f0 ff ff 	and    $0xfffffffffffff000,%r14
  16:	49 39 c6             	cmp    %rax,%r14
  19:	72 6b                	jb     0x86
  1b:	e8 95 cd b3 ff       	call   0xffb3cdb5
  20:	4c 39 f3             	cmp    %r14,%rbx
  23:	74 6e                	je     0x93
  25:	4c 89 64 24 10       	mov    %r12,0x10(%rsp)
* 2a:	44 8a 23             	mov    (%rbx),%r12b <-- trapping instruction
  2d:	43 0f b6 04 2f       	movzbl (%r15,%r13,1),%eax
  32:	84 c0                	test   %al,%al
  34:	75 18                	jne    0x4e
  36:	44 88 64 24 40       	mov    %r12b,0x40(%rsp)
  3b:	48                   	rex.W
  3c:	81                   	.byte 0x81
  3d:	c3                   	ret
  3e:	00 10                	add    %dl,(%rax)


---
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Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    e32cde8d2bd7 Merge tag 'sched_ext-for-6.12-rc1-fixes-1' of..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14ed139f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=286b31f2cf1c36b5
dashboard link: https://syzkaller.appspot.com/bug?extid=a6456f6334aa19425886
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=154e8927980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1244bdd0580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f7f2dc1bf47b/disk-e32cde8d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/063e4eafb554/vmlinux-e32cde8d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7ce38bae7b74/bzImage-e32cde8d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a6456f6334aa19425886@syzkaller.appspotmail.com

mmap: syz-executor813 (5232) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.
======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc1-syzkaller-00031-ge32cde8d2bd7 #0 Not tainted
------------------------------------------------------
syz-executor813/5232 is trying to acquire lock:
ffff88807bfa0198 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
ffff88807bfa0198 (&mm->mmap_lock){++++}-{3:3}, at: upgrade_mmap_lock_carefully+0xb6/0x160 mm/memory.c:6132

but task is already holding lock:
ffff888022786b48 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
ffff888022786b48 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: shmem_file_write_iter+0x80/0x120 mm/shmem.c:3211

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       down_write+0x99/0x220 kernel/locking/rwsem.c:1577
       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

-> #0 (&mm->mmap_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       down_write_killable+0xab/0x260 kernel/locking/rwsem.c:1588
       mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
       upgrade_mmap_lock_carefully+0xb6/0x160 mm/memory.c:6132
       lock_mm_and_find_vma+0x107/0x2f0 mm/memory.c:6185
       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+0x165/0x2b0
       fault_in_iov_iter_readable+0x229/0x280 lib/iov_iter.c:94
       generic_perform_write+0x259/0x6d0 mm/filemap.c:4044
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

2 locks held by syz-executor813/5232:
 #0: ffff88807b202420 (sb_writers#5){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2931 [inline]
 #0: ffff88807b202420 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0x224/0xc90 fs/read_write.c:679
 #1: ffff888022786b48 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
 #1: ffff888022786b48 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: shmem_file_write_iter+0x80/0x120 mm/shmem.c:3211

stack backtrace:
CPU: 0 UID: 0 PID: 5232 Comm: syz-executor813 Not tainted 6.12.0-rc1-syzkaller-00031-ge32cde8d2bd7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
 down_write_killable+0xab/0x260 kernel/locking/rwsem.c:1588
 mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
 upgrade_mmap_lock_carefully+0xb6/0x160 mm/memory.c:6132
 lock_mm_and_find_vma+0x107/0x2f0 mm/memory.c:6185
 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
RIP: 0010:fault_in_readable+0x165/0x2b0 mm/gup.c:2235
Code: b3 ff 4c 8d b3 ff 0f 00 00 48 89 d8 4d 01 e6 49 81 e6 00 f0 ff ff 49 39 c6 72 6b e8 65 ca b3 ff 4c 39 f3 74 6e 4c 89 64 24 10 <44> 8a 23 43 0f b6 04 2f 84 c0 75 18 44 88 64 24 40 48 81 c3 00 10
RSP: 0018:ffffc90003c3fa40 EFLAGS: 00050287
RAX: ffffffff81e1114b RBX: 0000000020001000 RCX: ffff88801cf78000
RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000000
RBP: ffffc90003c3faf8 R08: ffffffff81e110e8 R09: ffffffff84b94759
R10: 0000000000000002 R11: ffff88801cf78000 R12: 000000000000fecc
R13: dffffc0000000000 R14: 0000000020010000 R15: 1ffff92000787f50
 fault_in_iov_iter_readable+0x229/0x280 lib/iov_iter.c:94
 generic_perform_write+0x259/0x6d0 mm/filemap.c:4044
 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
RIP: 0033:0x7f355e2f2a19
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdd6291a88 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f355e33c11f RCX: 00007f355e2f2a19
RDX: 000000000000fecc RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00007f355e33c0fd R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020005000 R11: 0000000000000246 R12: 00007f355e34113c
R13: 00007f355e33c082 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
----------------
Code disassembly (best guess):
   0:	b3 ff                	mov    $0xff,%bl
   2:	4c 8d b3 ff 0f 00 00 	lea    0xfff(%rbx),%r14
   9:	48 89 d8             	mov    %rbx,%rax
   c:	4d 01 e6             	add    %r12,%r14
   f:	49 81 e6 00 f0 ff ff 	and    $0xfffffffffffff000,%r14
  16:	49 39 c6             	cmp    %rax,%r14
  19:	72 6b                	jb     0x86
  1b:	e8 65 ca b3 ff       	call   0xffb3ca85
  20:	4c 39 f3             	cmp    %r14,%rbx
  23:	74 6e                	je     0x93
  25:	4c 89 64 24 10       	mov    %r12,0x10(%rsp)
* 2a:	44 8a 23             	mov    (%rbx),%r12b <-- trapping instruction
  2d:	43 0f b6 04 2f       	movzbl (%r15,%r13,1),%eax
  32:	84 c0                	test   %al,%al
  34:	75 18                	jne    0x4e
  36:	44 88 64 24 40       	mov    %r12b,0x40(%rsp)
  3b:	48                   	rex.W
  3c:	81                   	.byte 0x81
  3d:	c3                   	ret
  3e:	00 10                	add    %dl,(%rax)


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[syzbot]

syzbot has bisected this issue to:

commit ea7e2d5e49c05e5db1922387b09ca74aa40f46e2
Author: Shu Han <ebpqwerty472123@gmail.com>
Date:   Tue Sep 17 09:41:04 2024 +0000

    mm: call the security_mmap_file() LSM hook in remap_file_pages()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1530539f980000
start commit:   e32cde8d2bd7 Merge tag 'sched_ext-for-6.12-rc1-fixes-1' of..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1730539f980000
console output: https://syzkaller.appspot.com/x/log.txt?x=1330539f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=286b31f2cf1c36b5
dashboard link: https://syzkaller.appspot.com/bug?extid=a6456f6334aa19425886
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=154e8927980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1244bdd0580000

Reported-by: syzbot+a6456f6334aa19425886@syzkaller.appspotmail.com
Fixes: ea7e2d5e49c0 ("mm: call the security_mmap_file() LSM hook in remap_file_pages()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[Shu Han]

It seems to be the same as [1].
New LSM hook position for remap_file_pages + IMA = deadlock.
The new LSM hook position is added for a bypass caused by
no check in remap_file_pages + READ_IMPLIES_EXEC in do_mmap.

I suggest fix it by removing the check and moving READ_IMPLIES_EXEC
out of do_mmap[2].

Link: https://lore.kernel.org/lkml/20240928065620.7abadb2d8552f03d785c77c9@linux-foundation.org/
[1]
Link: https://lore.kernel.org/all/20240928180044.50-1-ebpqwerty472123@gmail.com/
[2]

Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[Paul Moore]

On Wed, Oct 2, 2024 at 8:14 AM Shu Han <ebpqwerty472123@gmail.com> wrote:
>
> It seems to be the same as [1].
> New LSM hook position for remap_file_pages + IMA = deadlock.
> The new LSM hook position is added for a bypass caused by
> no check in remap_file_pages + READ_IMPLIES_EXEC in do_mmap.

Thanks Shu Han, let's mark this as a dup and sort out a fix in the first report.

#syz dup: [syzbot] [integrity?] [lsm?] possible deadlock in
process_measurement (4)

> I suggest fix it by removing the check and moving READ_IMPLIES_EXEC
> out of do_mmap[2].
>
> Link: https://lore.kernel.org/lkml/20240928065620.7abadb2d8552f03d785c77c9@linux-foundation.org/
> [1]
> Link: https://lore.kernel.org/all/20240928180044.50-1-ebpqwerty472123@gmail.com/
> [2]

-- 
paul-moore.com

Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[syzbot]

> On Wed, Oct 2, 2024 at 8:14 AM Shu Han <ebpqwerty472123@gmail.com> wrote:
>>
>> It seems to be the same as [1].
>> New LSM hook position for remap_file_pages + IMA = deadlock.
>> The new LSM hook position is added for a bypass caused by
>> no check in remap_file_pages + READ_IMPLIES_EXEC in do_mmap.
>
> Thanks Shu Han, let's mark this as a dup and sort out a fix in the first report.
>
> #syz dup: [syzbot] [integrity?] [lsm?] possible deadlock in

can't find the dup bug

> process_measurement (4)
>
>> I suggest fix it by removing the check and moving READ_IMPLIES_EXEC
>> out of do_mmap[2].
>>
>> Link: https://lore.kernel.org/lkml/20240928065620.7abadb2d8552f03d785c77c9@linux-foundation.org/
>> [1]
>> Link: https://lore.kernel.org/all/20240928180044.50-1-ebpqwerty472123@gmail.com/
>> [2]
>
> -- 
> paul-moore.com

Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

[Paul Moore]

On Wed, Oct 2, 2024 at 9:32 PM syzbot
<syzbot+a6456f6334aa19425886@syzkaller.appspotmail.com> wrote:
> > On Wed, Oct 2, 2024 at 8:14 AM Shu Han <ebpqwerty472123@gmail.com> wrote:
> >>
> >> It seems to be the same as [1].
> >> New LSM hook position for remap_file_pages + IMA = deadlock.
> >> The new LSM hook position is added for a bypass caused by
> >> no check in remap_file_pages + READ_IMPLIES_EXEC in do_mmap.
> >
> > Thanks Shu Han, let's mark this as a dup and sort out a fix in the first report.
> >
> > #syz dup: [syzbot] [integrity?] [lsm?] possible deadlock in
>
> can't find the dup bug
>
> > process_measurement (4)

Stupid line wrapping, let's try again ...

#syz dup: possible deadlock in process_measurement (4)

> >> I suggest fix it by removing the check and moving READ_IMPLIES_EXEC
> >> out of do_mmap[2].
> >>
> >> Link: https://lore.kernel.org/lkml/20240928065620.7abadb2d8552f03d785c77c9@linux-foundation.org/
> >> [1]
> >> Link: https://lore.kernel.org/all/20240928180044.50-1-ebpqwerty472123@gmail.com/
> >> [2]

-- 
paul-moore.com