loop0: detected capacity change from 0 to 1024 Zero length message leads to an empty skb ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.0/5337 is trying to acquire lock: ffff888037a880b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfsplus_find_init+0x168/0x2d0 fs/hfsplus/bfind.c:28 but task is already holding lock: ffff888035eee2c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2b3/0xc30 fs/hfsplus/extents.c:573 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 hfsplus_file_extend+0x215/0x1d70 fs/hfsplus/extents.c:453 hfsplus_bmap_reserve+0x125/0x510 fs/hfsplus/btree.c:358 __hfsplus_ext_write_extent+0x28d/0x5b0 fs/hfsplus/extents.c:104 __hfsplus_ext_cache_extent+0x89/0xe30 fs/hfsplus/extents.c:186 hfsplus_ext_read_extent fs/hfsplus/extents.c:218 [inline] hfsplus_file_extend+0x4af/0x1d70 fs/hfsplus/extents.c:457 hfsplus_get_block+0x42c/0x1670 fs/hfsplus/extents.c:245 __block_write_begin_int+0x6c6/0x1910 fs/buffer.c:2142 block_write_begin fs/buffer.c:2253 [inline] cont_write_begin+0x737/0xae0 fs/buffer.c:2591 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48 cont_expand_zero fs/buffer.c:2519 [inline] cont_write_begin+0x2e7/0xae0 fs/buffer.c:2581 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48 generic_cont_expand_simple+0x146/0x210 fs/buffer.c:2482 hfsplus_setattr+0x169/0x270 fs/hfsplus/inode.c:280 notify_change+0xc1a/0xf40 fs/attr.c:556 do_truncate+0x1c2/0x250 fs/open.c:68 do_ftruncate+0x4db/0x5c0 fs/open.c:196 do_sys_ftruncate fs/open.c:208 [inline] __do_sys_ftruncate fs/open.c:213 [inline] __se_sys_ftruncate fs/open.c:211 [inline] __x64_sys_ftruncate+0x92/0xf0 fs/open.c:211 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&tree->tree_lock/1){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 hfsplus_find_init+0x168/0x2d0 fs/hfsplus/bfind.c:28 hfsplus_file_truncate+0x39b/0xc30 fs/hfsplus/extents.c:579 hfsplus_setattr+0x1c4/0x270 fs/hfsplus/inode.c:286 notify_change+0xc1a/0xf40 fs/attr.c:556 do_truncate+0x1c2/0x250 fs/open.c:68 do_ftruncate+0x4db/0x5c0 fs/open.c:196 do_sys_ftruncate fs/open.c:208 [inline] __do_sys_ftruncate fs/open.c:213 [inline] __se_sys_ftruncate fs/open.c:211 [inline] __x64_sys_ftruncate+0x92/0xf0 fs/open.c:211 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&HFSPLUS_I(inode)->extents_lock); lock(&tree->tree_lock/1); lock(&HFSPLUS_I(inode)->extents_lock); lock(&tree->tree_lock/1); *** DEADLOCK *** 3 locks held by syz.0.0/5337: #0: ffff8880121fa420 (sb_writers#12){.+.+}-{0:0}, at: class_super_write_constructor include/linux/fs/super.h:128 [inline] #0: ffff8880121fa420 (sb_writers#12){.+.+}-{0:0}, at: do_ftruncate+0x47c/0x5c0 fs/open.c:195 #1: ffff888035eee4b8 (&sb->s_type->i_mutex_key#25){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1033 [inline] #1: ffff888035eee4b8 (&sb->s_type->i_mutex_key#25){+.+.}-{4:4}, at: do_truncate+0x18f/0x250 fs/open.c:63 #2: ffff888035eee2c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2b3/0xc30 fs/hfsplus/extents.c:573 stack backtrace: CPU: 0 UID: 0 PID: 5337 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 hfsplus_find_init+0x168/0x2d0 fs/hfsplus/bfind.c:28 hfsplus_file_truncate+0x39b/0xc30 fs/hfsplus/extents.c:579 hfsplus_setattr+0x1c4/0x270 fs/hfsplus/inode.c:286 notify_change+0xc1a/0xf40 fs/attr.c:556 do_truncate+0x1c2/0x250 fs/open.c:68 do_ftruncate+0x4db/0x5c0 fs/open.c:196 do_sys_ftruncate fs/open.c:208 [inline] __do_sys_ftruncate fs/open.c:213 [inline] __se_sys_ftruncate fs/open.c:211 [inline] __x64_sys_ftruncate+0x92/0xf0 fs/open.c:211 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3369b9c819 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f336a982fe8 EFLAGS: 00000246 ORIG_RAX: 000000000000004d RAX: ffffffffffffffda RBX: 00007f3369e15fa0 RCX: 00007f3369b9c819 RDX: 0000000000000000 RSI: 0000000002007ffb RDI: 0000000000000007 RBP: 00007f3369c32c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3369e16038 R14: 00007f3369e15fa0 R15: 00007ffead7116d8