audit: type=1400 audit(1574474105.485:99): avc: denied { map } for pid=12539 comm="syz-executor.4" path="/dev/ashmem" dev="devtmpfs" ino=5461 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:device_t:s0 tclass=chr_file permissive=1 ====================================================== binder: 12531:12538 BC_CLEAR_DEATH_NOTIFICATION invalid ref 0 WARNING: possible circular locking dependency detected 4.14.155-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/12543 is trying to acquire lock: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000853928d7>] inode_lock include/linux/fs.h:724 [inline] (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000853928d7>] shmem_fallocate+0x150/0xae0 mm/shmem.c:2904 but task is already holding lock: (ashmem_mutex){+.+.}, at: [<00000000b02fdb3b>] ashmem_shrink_scan+0x53/0x4f0 drivers/staging/android/ashmem.c:446 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (ashmem_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 ashmem_mmap+0x4c/0x450 drivers/staging/android/ashmem.c:369 call_mmap include/linux/fs.h:1803 [inline] mmap_region+0x7d9/0xfb0 mm/mmap.c:1736 do_mmap+0x548/0xb80 mm/mmap.c:1512 do_mmap_pgoff include/linux/mm.h:2215 [inline] vm_mmap_pgoff+0x177/0x1c0 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1564 [inline] SyS_mmap_pgoff+0xf4/0x1b0 mm/mmap.c:1520 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (&mm->mmap_sem){++++}: down_read+0x37/0xa0 kernel/locking/rwsem.c:24 __do_page_fault+0x8a4/0xbb0 arch/x86/mm/fault.c:1356 page_fault+0x22/0x50 arch/x86/entry/entry_64.S:1122 fault_in_pages_readable include/linux/pagemap.h:606 [inline] iov_iter_fault_in_readable+0x162/0x350 lib/iov_iter.c:421 generic_perform_write+0x158/0x460 mm/filemap.c:3123 __generic_file_write_iter+0x32e/0x550 mm/filemap.c:3258 generic_file_write_iter+0x36f/0x650 mm/filemap.c:3286 call_write_iter include/linux/fs.h:1798 [inline] new_sync_write fs/read_write.c:471 [inline] __vfs_write+0x401/0x5a0 fs/read_write.c:484 vfs_write+0x17f/0x4d0 fs/read_write.c:546 SYSC_write fs/read_write.c:594 [inline] SyS_write+0x102/0x250 fs/read_write.c:586 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&sb->s_type->i_mutex_key binder: 12531:12538 unknown command 0 #10){+.+.}: lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3994 down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:724 [inline] shmem_fallocate+0x150/0xae0 mm/shmem.c:2904 binder: 12531:12538 ioctl c0306201 20000480 returned -22 ashmem_shrink_scan drivers/staging/android/ashmem.c:453 [inline] ashmem_shrink_scan+0x1ca/0x4f0 drivers/staging/android/ashmem.c:437 ashmem_ioctl+0x2b4/0xd20 drivers/staging/android/ashmem.c:795 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#10 --> &mm->mmap_sem --> ashmem_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ashmem_mutex); lock(&mm->mmap_sem); lock(ashmem_mutex); lock(&sb->s_type->i_mutex_key#10); *** DEADLOCK *** 1 lock held by syz-executor.4/12543: #0: (ashmem_mutex){+.+.}, at: [<00000000b02fdb3b>] ashmem_shrink_scan+0x53/0x4f0 drivers/staging/android/ashmem.c:446 stack backtrace: CPU: 1 PID: 12543 Comm: syz-executor.4 Not tainted 4.14.155-syzkaller #0 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xe5/0x154 lib/dump_stack.c:58 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2f5f/0x4320 kernel/locking/lockdep.c:3487 lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3994 down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:724 [inline] shmem_fallocate+0x150/0xae0 mm/shmem.c:2904 ashmem_shrink_scan drivers/staging/android/ashmem.c:453 [inline] ashmem_shrink_scan+0x1ca/0x4f0 drivers/staging/android/ashmem.c:437 ashmem_ioctl+0x2b4/0xd20 drivers/staging/android/ashmem.c:795 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a639 RSP: 002b:00007f54928dbc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a639 RDX: 0000000000000000 RSI: 000000000000770a RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f54928dc6d4 R13: 00000000004c1dd4 R14: 00000000004d5d28 R15: 00000000ffffffff binder: BINDER_SET_CONTEXT_MGR already set binder: 12552:12557 ioctl 40046207 0 returned -16 binder: 12552:12557 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 12552:12557 unknown command 0 binder: 12552:12557 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 12552:12557 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12572:12579 ioctl 40046207 0 returned -16 binder: 12572:12579 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 12572:12579 unknown command 0 binder: 12572:12579 ioctl c0306201 20000480 returned -22 sock: process `syz-executor.5' is using obsolete setsockopt SO_BSDCOMPAT binder: BINDER_SET_CONTEXT_MGR already set binder: 12614:12622 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12644:12648 ioctl 40046207 0 returned -16 binder: 12644:12648 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 12644:12648 unknown command 0 binder: 12644:12648 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 12660:12663 ioctl 40046207 0 returned -16 binder: 12660:12663 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 12660:12663 unknown command 0 binder: 12660:12663 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 12686:12695 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12717:12723 ioctl 40046207 0 returned -16 binder: 12717:12723 BC_CLEAR_DEATH_NOTIFICATION invalid ref 0 binder: 12717:12723 unknown command 0 binder: 12717:12723 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 12751:12755 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12778:12782 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12800:12802 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12827:12833 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12856:12860 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12897:12903 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12930:12935 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12949:12953 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 12949:12953 ioctl 40046207 0 returned -16 binder: 12949:12953 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 12949:12953 unknown command 0 binder: 12949:12953 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 12995:12999 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 13020:13021 ioctl 40046207 0 returned -16 binder: 13020:13021 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 13020:13021 unknown command 2095323 binder: 13020:13021 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13029:13036 ioctl 40046207 0 returned -16 binder: 13029:13036 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 13029:13036 unknown command 0 binder: 13029:13036 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13029:13036 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 13072:13077 ioctl 40046207 0 returned -16 binder: 13072:13077 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 13072:13077 unknown command 0 binder: 13072:13077 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13108:13116 ioctl 40046207 0 returned -16 binder: 13108:13116 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 13108:13116 unknown command 0 binder: 13108:13116 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13133:13137 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 13151:13154 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 13172:13176 ioctl 40046207 0 returned -16 binder: 13172:13176 ioctl 8953 200000c0 returned -22 binder: 13172:13176 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 13172:13176 unknown command 0 binder: 13172:13176 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13178:13183 ioctl 40046207 0 returned -16 binder: 13178:13193 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 13178:13193 unknown command 0 binder: 13178:13193 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13212:13218 ioctl 40046207 0 returned -16 binder: 13212:13218 BC_CLEAR_DEATH_NOTIFICATION death notification not active binder: 13212:13218 unknown command 0 binder: 13212:13218 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13244:13249 ioctl 40046207 0 returned -16 binder: 13244:13249 unknown command 0 binder: 13244:13249 ioctl c0306201 20000480 returned -22 binder: BINDER_SET_CONTEXT_MGR already set binder: 13262:13265 ioctl 40046207 0 returned -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 13280:13284 ioctl 40046207 0 returned -16 binder: 13280:13284 unknown command -88312315 binder: 13280:13284 ioctl c0306201 20000200 returned -22 binder: 13280:13284 BC_CLEAR_DEATH_NOTIFICATION invalid ref 32 binder: 13280:13284 unknown command 0 binder: 13280:13284 ioctl c0306201 20000480 returned -22