[syzbot] [fat?] possible deadlock in do_user_addr_fault

From: syzbot
Date: Tue Mar 28 2023 - 15:53:18 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 3a93e40326c8 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=126b5661c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d40b592130bb7abb
dashboard link: https://syzkaller.appspot.com/bug?extid=278098b0faaf0595072b
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1e4e99f83edc/disk-3a93e403.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dd7a2ef894d8/vmlinux-3a93e403.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8054ad68a13e/bzImage-3a93e403.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+278098b0faaf0595072b@xxxxxxxxxxxxxxxxxxxxxxxxx

exFAT-fs (loop5): failed to load upcase table (idx : 0x00010000, chksum : 0xac19d315, utbl_chksum : 0xe619d30d)
======================================================
WARNING: possible circular locking dependency detected
6.3.0-rc4-syzkaller-00025-g3a93e40326c8 #0 Not tainted
------------------------------------------------------
syz-executor.5/29002 is trying to acquire lock:
ffff88807c924b98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
ffff88807c924b98 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0xa51/0x1230 arch/x86/mm/fault.c:1358

but task is already holding lock:
ffff88807b0f20e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_iterate+0x111/0xb40 fs/exfat/dir.c:232

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&sbi->s_lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
exfat_get_block+0x18d/0x16e0 fs/exfat/inode.c:280
do_mpage_readpage+0x768/0x1960 fs/mpage.c:208
mpage_readahead+0x344/0x580 fs/mpage.c:356
read_pages+0x1a2/0xd40 mm/readahead.c:161
page_cache_ra_unbounded+0x477/0x5e0 mm/readahead.c:270
do_page_cache_ra mm/readahead.c:300 [inline]
page_cache_ra_order+0x6ec/0xa00 mm/readahead.c:560
ondemand_readahead+0x6b3/0x1080 mm/readahead.c:682
page_cache_sync_ra+0x1c9/0x200 mm/readahead.c:709
page_cache_sync_readahead include/linux/pagemap.h:1214 [inline]
filemap_get_pages+0x28d/0x1620 mm/filemap.c:2598
filemap_read+0x35e/0xc70 mm/filemap.c:2693
generic_file_read_iter+0x3ad/0x5b0 mm/filemap.c:2840
__kernel_read+0x2ca/0x830 fs/read_write.c:428
integrity_kernel_read+0x7f/0xb0 security/integrity/iint.c:199
ima_calc_file_hash_tfm+0x2aa/0x3b0 security/integrity/ima/ima_crypto.c:485
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0x195/0x4a0 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x55b/0x670 security/integrity/ima/ima_api.c:293
process_measurement+0xd2f/0x1930 security/integrity/ima/ima_main.c:341
ima_file_check+0xba/0x100 security/integrity/ima/ima_main.c:539
do_open fs/namei.c:3562 [inline]
path_openat+0x15d3/0x2750 fs/namei.c:3715
do_filp_open+0x1ba/0x410 fs/namei.c:3742
do_sys_openat2+0x16d/0x4c0 fs/open.c:1348
do_sys_open fs/open.c:1364 [inline]
__do_sys_openat fs/open.c:1380 [inline]
__se_sys_openat fs/open.c:1375 [inline]
__x64_sys_openat+0x143/0x1f0 fs/open.c:1375
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (mapping.invalidate_lock#9){.+.+}-{3:3}:
down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
filemap_invalidate_lock_shared include/linux/fs.h:813 [inline]
filemap_fault+0xb99/0x2450 mm/filemap.c:3274
__do_fault+0x107/0x600 mm/memory.c:4141
do_read_fault mm/memory.c:4492 [inline]
do_fault mm/memory.c:4621 [inline]
handle_pte_fault mm/memory.c:4909 [inline]
__handle_mm_fault+0x24f3/0x3e60 mm/memory.c:5051
handle_mm_fault+0x2ba/0x9c0 mm/memory.c:5197
do_user_addr_fault+0x475/0x1230 arch/x86/mm/fault.c:1407
handle_page_fault arch/x86/mm/fault.c:1498 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1554
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
do_strncpy_from_user lib/strncpy_from_user.c:41 [inline]
strncpy_from_user+0x1c1/0x3c0 lib/strncpy_from_user.c:139
getname_flags.part.0+0x95/0x4f0 fs/namei.c:151
getname_flags include/linux/audit.h:321 [inline]
getname+0x92/0xd0 fs/namei.c:219
do_sys_openat2+0xf5/0x4c0 fs/open.c:1342
do_sys_open fs/open.c:1364 [inline]
__do_sys_openat fs/open.c:1380 [inline]
__se_sys_openat fs/open.c:1375 [inline]
__x64_sys_openat+0x143/0x1f0 fs/open.c:1375
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&mm->mmap_lock){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
lock_acquire kernel/locking/lockdep.c:5669 [inline]
lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634
down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
mmap_read_lock include/linux/mmap_lock.h:117 [inline]
do_user_addr_fault+0xa51/0x1230 arch/x86/mm/fault.c:1358
handle_page_fault arch/x86/mm/fault.c:1498 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1554
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
filldir+0x1ec/0x680 fs/readdir.c:253
dir_emit_dot include/linux/fs.h:3144 [inline]
dir_emit_dots include/linux/fs.h:3155 [inline]
exfat_iterate+0x56b/0xb40 fs/exfat/dir.c:235
iterate_dir+0x1fd/0x6f0 fs/readdir.c:67
__do_sys_getdents fs/readdir.c:286 [inline]
__se_sys_getdents fs/readdir.c:271 [inline]
__x64_sys_getdents+0x13e/0x2c0 fs/readdir.c:271
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
&mm->mmap_lock --> mapping.invalidate_lock#9 --> &sbi->s_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&sbi->s_lock);
lock(mapping.invalidate_lock#9);
lock(&sbi->s_lock);
lock(&mm->mmap_lock);

*** DEADLOCK ***

3 locks held by syz-executor.5/29002:
#0: ffff88801e0019e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe7/0x100 fs/file.c:1047
#1: ffff88803cc2d0b0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: iterate_dir+0x504/0x6f0 fs/readdir.c:57
#2: ffff88807b0f20e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_iterate+0x111/0xb40 fs/exfat/dir.c:232

stack backtrace:
CPU: 0 PID: 29002 Comm: syz-executor.5 Not tainted 6.3.0-rc4-syzkaller-00025-g3a93e40326c8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
lock_acquire kernel/locking/lockdep.c:5669 [inline]
lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634
down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
mmap_read_lock include/linux/mmap_lock.h:117 [inline]
do_user_addr_fault+0xa51/0x1230 arch/x86/mm/fault.c:1358
handle_page_fault arch/x86/mm/fault.c:1498 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1554
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:filldir+0x1ec/0x680 fs/readdir.c:253
Code: 48 89 c6 48 89 44 24 20 e8 e1 c3 9a ff 48 8b 44 24 20 49 39 c6 0f 87 44 02 00 00 e8 de c7 9a ff 0f 01 cb 0f ae e8 48 8b 04 24 <49> 89 46 08 e8 cb c7 9a ff 4c 8b 74 24 38 48 8b 7c 24 10 49 89 3e
RSP: 0018:ffffc9000b04fc00 EFLAGS: 00050202
RAX: 0000000000000000 RBX: ffffc9000b04fe98 RCX: ffffc90014ab2000
RDX: 0000000000040000 RSI: ffffffff81e81072 RDI: 0000000000000006
RBP: 0000000000000001 R08: 0000000000000006 R09: 0000000020001fc0
R10: 00007fffffffefe8 R11: 0000000000000002 R12: 0000000000000018
R13: ffffffff8a65d5c0 R14: 0000000020001fc0 R15: 0000000000000018
dir_emit_dot include/linux/fs.h:3144 [inline]
dir_emit_dots include/linux/fs.h:3155 [inline]
exfat_iterate+0x56b/0xb40 fs/exfat/dir.c:235
iterate_dir+0x1fd/0x6f0 fs/readdir.c:67
__do_sys_getdents fs/readdir.c:286 [inline]
__se_sys_getdents fs/readdir.c:271 [inline]
__x64_sys_getdents+0x13e/0x2c0 fs/readdir.c:271
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fead2a8c0f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fead388c168 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007fead2babf80 RCX: 00007fead2a8c0f9
RDX: 00000000000000b8 RSI: 0000000020001fc0 RDI: 0000000000000006
RBP: 00007fead2ae7b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc3d6931df R14: 00007fead388c300 R15: 0000000000022000
</TASK>
exFAT-fs (loop5): error, invalid access to FAT (entry 0x00000005) bogus content (0x91852372)
exFAT-fs (loop5): Filesystem has been set read-only
exFAT-fs (loop5): error, invalid access to FAT (entry 0x00000005) bogus content (0x91852372)
----------------
Code disassembly (best guess):
0: 48 89 c6 mov %rax,%rsi
3: 48 89 44 24 20 mov %rax,0x20(%rsp)
8: e8 e1 c3 9a ff callq 0xff9ac3ee
d: 48 8b 44 24 20 mov 0x20(%rsp),%rax
12: 49 39 c6 cmp %rax,%r14
15: 0f 87 44 02 00 00 ja 0x25f
1b: e8 de c7 9a ff callq 0xff9ac7fe
20: 0f 01 cb stac
23: 0f ae e8 lfence
26: 48 8b 04 24 mov (%rsp),%rax
* 2a: 49 89 46 08 mov %rax,0x8(%r14) <-- trapping instruction
2e: e8 cb c7 9a ff callq 0xff9ac7fe
33: 4c 8b 74 24 38 mov 0x38(%rsp),%r14
38: 48 8b 7c 24 10 mov 0x10(%rsp),%rdi
3d: 49 89 3e mov %rdi,(%r14)

---
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