====================================================== WARNING: possible circular locking dependency detected 4.14.275-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/9532 is trying to acquire lock: (sb_writers#6){.+.+}, at: [] file_start_write include/linux/fs.h:2714 [inline] (sb_writers#6){.+.+}, at: [] vfs_fallocate+0x5c1/0x790 fs/open.c:318 but task is already holding lock: (ashmem_mutex){+.+.}, at: [] ashmem_shrink_scan drivers/staging/android/ashmem.c:494 [inline] (ashmem_mutex){+.+.}, at: [] ashmem_ioctl+0x27e/0xd00 drivers/staging/android/ashmem.c:843 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (ashmem_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 ashmem_mmap+0x50/0x5c0 drivers/staging/android/ashmem.c:393 call_mmap include/linux/fs.h:1785 [inline] mmap_region+0xa1a/0x1220 mm/mmap.c:1717 do_mmap+0x5b3/0xcb0 mm/mmap.c:1495 do_mmap_pgoff include/linux/mm.h:2185 [inline] vm_mmap_pgoff+0x14e/0x1a0 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1545 [inline] SyS_mmap_pgoff+0x249/0x510 mm/mmap.c:1503 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb hrtimer: interrupt took 26279 ns -> #2 (&mm->mmap_sem){++++}: L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details. __might_fault mm/memory.c:4687 [inline] __might_fault+0x137/0x1b0 mm/memory.c:4672 _copy_to_user+0x27/0xd0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] filldir+0x1d5/0x390 fs/readdir.c:237 dir_emit_dot include/linux/fs.h:3361 [inline] dir_emit_dots include/linux/fs.h:3372 [inline] dcache_readdir+0x180/0x860 fs/libfs.c:192 iterate_dir+0x1a0/0x5e0 fs/readdir.c:52 SYSC_getdents fs/readdir.c:272 [inline] SyS_getdents+0x125/0x240 fs/readdir.c:253 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #1 (&type->i_mutex_dir_key#5){++++}: down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:719 [inline] do_last fs/namei.c:3331 [inline] path_openat+0xde2/0x2970 fs/namei.c:3569 do_filp_open+0x179/0x3c0 fs/namei.c:3603 do_sys_open+0x296/0x410 fs/open.c:1081 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #0 (sb_writers#6){.+.+}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x64/0x260 fs/super.c:1342 file_start_write include/linux/fs.h:2714 [inline] vfs_fallocate+0x5c1/0x790 fs/open.c:318 ashmem_shrink_scan.part.0+0x135/0x3d0 drivers/staging/android/ashmem.c:501 ashmem_shrink_scan drivers/staging/android/ashmem.c:494 [inline] ashmem_ioctl+0x294/0xd00 drivers/staging/android/ashmem.c:843 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb other info that might help us debug this: Chain exists of: sb_writers#6 --> &mm->mmap_sem --> ashmem_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ashmem_mutex); lock(&mm->mmap_sem); lock(ashmem_mutex); lock(sb_writers#6); *** DEADLOCK *** 1 lock held by syz-executor.1/9532: #0: (ashmem_mutex){+.+.}, at: [] ashmem_shrink_scan drivers/staging/android/ashmem.c:494 [inline] #0: (ashmem_mutex){+.+.}, at: [] ashmem_ioctl+0x27e/0xd00 drivers/staging/android/ashmem.c:843 stack backtrace: CPU: 0 PID: 9532 Comm: syz-executor.1 Not tainted 4.14.275-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x64/0x260 fs/super.c:1342 file_start_write include/linux/fs.h:2714 [inline] vfs_fallocate+0x5c1/0x790 fs/open.c:318 ashmem_shrink_scan.part.0+0x135/0x3d0 drivers/staging/android/ashmem.c:501 ashmem_shrink_scan drivers/staging/android/ashmem.c:494 [inline] ashmem_ioctl+0x294/0xd00 drivers/staging/android/ashmem.c:843 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fafc9e930e9 RSP: 002b:00007fafc8808168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fafc9fa5f60 RCX: 00007fafc9e930e9 RDX: 0000000000000000 RSI: 000000000000770a RDI: 0000000000000003 RBP: 00007fafc9eed08d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd9ffab24f R14: 00007fafc8808300 R15: 0000000000022000 netlink: 8 bytes leftover after parsing attributes in process `syz-executor.1'. overlayfs: fs on 'file0' does not support file handles, falling back to index=off. EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue FAT-fs (loop5): bogus number of reserved sectors FAT-fs (loop5): Can't find a valid FAT filesystem audit: type=1107 audit(1650253935.117:3): pid=10171 uid=0 auid=4294967295 ses=4294967295 msg='m7rK•­p# ÞÓ¯' can: request_module (can-proto-0) failed. Unknown ioctl -1070571007 9pnet: Insufficient options for proto=fd FAT-fs (loop3): Unrecognized mount option "uid<00000000000000060929" or missing value Zero length message leads to an empty skb Unknown ioctl 35096 audit: type=1107 audit(1650253939.517:4): pid=10719 uid=0 auid=4294967295 ses=4294967295 msg='Î' audit: type=1107 audit(1650253939.557:5): pid=10731 uid=0 auid=4294967295 ses=4294967295 msg='Î' audit: type=1107 audit(1650253939.597:6): pid=10744 uid=0 auid=4294967295 ses=4294967295 msg='Î' audit: type=1107 audit(1650253939.627:7): pid=10753 uid=0 auid=4294967295 ses=4294967295 msg='Î' Bluetooth: hci0 command 0x0401 tx timeout 9pnet: Insufficient options for proto=fd hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: unknown main item tag 0x0 hid-generic 0000:0000:0000.0001: hidraw0: HID v0.00 Device [syz1] on syz1 9pnet: Insufficient options for proto=fd audit: type=1107 audit(1650253941.157:8): pid=10972 uid=0 auid=4294967295 ses=4294967295 msg='' FAT-fs (loop1): bogus number of reserved sectors FAT-fs (loop1): Can't find a valid FAT filesystem