Re: [syzbot] [fat?] possible deadlock in do_user_addr_fault

From: syzbot
Date: Tue Jun 06 2023 - 04:24:24 EST

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syzbot has found a reproducer for the following issue on:

HEAD commit: f8dba31b0a82 Merge tag 'asym-keys-fix-for-linus-v6.4-rc5' ..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13cd961d280000
kernel config: https://syzkaller.appspot.com/x/.config?x=3c980bfe8b399968
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
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=144ccf79280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=135fab79280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0aac0833aa9d/disk-f8dba31b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/06f1060b83c8/vmlinux-f8dba31b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8450975febdf/bzImage-f8dba31b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/a0a6e4ccb5ba/mount_0.gz

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

======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc5-syzkaller-00002-gf8dba31b0a82 #0 Not tainted
------------------------------------------------------
syz-executor181/5187 is trying to acquire lock:
ffff88807ac63768 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:142 [inline]
ffff88807ac63768 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0xb3d/0x1210 arch/x86/mm/fault.c:1391

but task is already holding lock:
ffff88801e4a00e0 (&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:234
mpage_readahead+0x344/0x580 fs/mpage.c:382
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:1211 [inline]
filemap_get_pages+0x28d/0x1620 mm/filemap.c:2595
filemap_read+0x35e/0xc70 mm/filemap.c:2690
generic_file_read_iter+0x3ad/0x5b0 mm/filemap.c:2837
__kernel_read+0x2ca/0x830 fs/read_write.c:428
integrity_kernel_read+0x7f/0xb0 security/integrity/iint.c:192
ima_calc_file_hash_tfm+0x2b3/0x3c0 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:3638 [inline]
path_openat+0x15d3/0x2750 fs/namei.c:3791
do_filp_open+0x1ba/0x410 fs/namei.c:3818
do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x143/0x1f0 fs/open.c:1383
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#3){.+.+}-{3:3}:
down_read+0x9c/0x480 kernel/locking/rwsem.c:1520
filemap_invalidate_lock_shared include/linux/fs.h:830 [inline]
filemap_fault+0xbba/0x24c0 mm/filemap.c:3271
__do_fault+0x107/0x600 mm/memory.c:4176
do_read_fault mm/memory.c:4530 [inline]
do_fault mm/memory.c:4659 [inline]
do_pte_missing mm/memory.c:3647 [inline]
handle_pte_fault mm/memory.c:4947 [inline]
__handle_mm_fault+0x28bc/0x41c0 mm/memory.c:5089
handle_mm_fault+0x2af/0x9f0 mm/memory.c:5243
faultin_page mm/gup.c:925 [inline]
__get_user_pages+0x60a/0x10e0 mm/gup.c:1147
__get_user_pages_locked mm/gup.c:1381 [inline]
__gup_longterm_locked+0x720/0x2420 mm/gup.c:2079
pin_user_pages_remote+0x101/0x160 mm/gup.c:3124
process_vm_rw_single_vec mm/process_vm_access.c:105 [inline]
process_vm_rw_core.constprop.0+0x43b/0x990 mm/process_vm_access.c:215
process_vm_rw+0x29c/0x300 mm/process_vm_access.c:283
__do_sys_process_vm_readv mm/process_vm_access.c:295 [inline]
__se_sys_process_vm_readv mm/process_vm_access.c:291 [inline]
__x64_sys_process_vm_readv+0xe3/0x1b0 mm/process_vm_access.c:291
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:3113 [inline]
check_prevs_add kernel/locking/lockdep.c:3232 [inline]
validate_chain kernel/locking/lockdep.c:3847 [inline]
__lock_acquire+0x2fcd/0x5f30 kernel/locking/lockdep.c:5088
lock_acquire kernel/locking/lockdep.c:5705 [inline]
lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5670
down_read+0x9c/0x480 kernel/locking/rwsem.c:1520
mmap_read_lock include/linux/mmap_lock.h:142 [inline]
do_user_addr_fault+0xb3d/0x1210 arch/x86/mm/fault.c:1391
handle_page_fault arch/x86/mm/fault.c:1534 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
filldir64+0x291/0x5d0 fs/readdir.c:335
dir_emit_dot include/linux/fs.h:3163 [inline]
dir_emit_dots include/linux/fs.h:3174 [inline]
exfat_iterate+0x56b/0xb40 fs/exfat/dir.c:235
iterate_dir+0x1fd/0x6f0 fs/readdir.c:67
__do_sys_getdents64 fs/readdir.c:369 [inline]
__se_sys_getdents64 fs/readdir.c:354 [inline]
__x64_sys_getdents64+0x13e/0x2c0 fs/readdir.c:354
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#3 --> &sbi->s_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&sbi->s_lock);
lock(mapping.invalidate_lock#3);
lock(&sbi->s_lock);
rlock(&mm->mmap_lock);

*** DEADLOCK ***

3 locks held by syz-executor181/5187:
#0: ffff88802aa4c868 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe7/0x100 fs/file.c:1047
#1: ffff8880700077b0 (&sb->s_type->i_mutex_key#15){++++}-{3:3}, at: iterate_dir+0x504/0x6f0 fs/readdir.c:57
#2: ffff88801e4a00e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_iterate+0x111/0xb40 fs/exfat/dir.c:232

stack backtrace:
CPU: 0 PID: 5187 Comm: syz-executor181 Not tainted 6.4.0-rc5-syzkaller-00002-gf8dba31b0a82 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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:2188
check_prev_add kernel/locking/lockdep.c:3113 [inline]
check_prevs_add kernel/locking/lockdep.c:3232 [inline]
validate_chain kernel/locking/lockdep.c:3847 [inline]
__lock_acquire+0x2fcd/0x5f30 kernel/locking/lockdep.c:5088
lock_acquire kernel/locking/lockdep.c:5705 [inline]
lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5670
down_read+0x9c/0x480 kernel/locking/rwsem.c:1520
mmap_read_lock include/linux/mmap_lock.h:142 [inline]
do_user_addr_fault+0xb3d/0x1210 arch/x86/mm/fault.c:1391
handle_page_fault arch/x86/mm/fault.c:1534 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:filldir64+0x291/0x5d0 fs/readdir.c:335
Code: 02 41 83 e7 01 44 89 fe e8 9c c2 98 ff 45 84 ff 0f 84 9a fe ff ff e9 40 ff ff ff e8 a9 c6 98 ff 0f 01 cb 0f ae e8 48 8b 04 24 <49> 89 47 08 e8 96 c6 98 ff 4c 8b 7c 24 28 48 8b 7c 24 10 49 89 3f
RSP: 0018:ffffc90003c5fbf8 EFLAGS: 00050293
RAX: 0000000000000000 RBX: ffffc90003c5fe98 RCX: 0000000000000000
RDX: ffff88801fa55940 RSI: ffffffff81eb7f97 RDI: 0000000000000006
RBP: 0000000000000018 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000000018 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000018 R14: ffffffff8a662e00 R15: 0000000000000000
dir_emit_dot include/linux/fs.h:3163 [inline]
dir_emit_dots include/linux/fs.h:3174 [inline]
exfat_iterate+0x56b/0xb40 fs/exfat/dir.c:235
iterate_dir+0x1fd/0x6f0 fs/readdir.c:67
__do_sys_getdents64 fs/readdir.c:369 [inline]
__se_sys_getdents64 fs/readdir.c:354 [inline]
__x64_sys_getdents64+0x13e/0x2c0 fs/readdir.c:354
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: 0033:0x7f804978aab9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 71 15 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:00007f8041335208 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f80498107b8 RCX: 00007f804978aab9
RDX: 0000000000008008 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f80498107b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f80498107bc
R13: 00007fff6d2c4cff R14: 00007f8041335300 R15: 0000000000022000
</TASK>
----------------
Code disassembly (best guess):
0: 02 41 83 add -0x7d(%rcx),%al
3: e7 01 out %eax,$0x1
5: 44 89 fe mov %r15d,%esi
8: e8 9c c2 98 ff callq 0xff98c2a9
d: 45 84 ff test %r15b,%r15b
10: 0f 84 9a fe ff ff je 0xfffffeb0
16: e9 40 ff ff ff jmpq 0xffffff5b
1b: e8 a9 c6 98 ff callq 0xff98c6c9
20: 0f 01 cb stac
23: 0f ae e8 lfence
26: 48 8b 04 24 mov (%rsp),%rax
* 2a: 49 89 47 08 mov %rax,0x8(%r15) <-- trapping instruction
2e: e8 96 c6 98 ff callq 0xff98c6c9
33: 4c 8b 7c 24 28 mov 0x28(%rsp),%r15
38: 48 8b 7c 24 10 mov 0x10(%rsp),%rdi
3d: 49 89 3f mov %rdi,(%r15)

---
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Next message: David Laight: "RE: Direct rdtsc call side-effect"
Previous message: Aradhya Bhatia: "[PATCH v7 6/8] drm/bridge: sii902x: Set input_bus_flags in atomic_check"
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