======================================================
[ INFO: possible circular locking dependency detected ]
4.4.120-gd63fdf6 #28 Not tainted
-------------------------------------------------------
syz-executor0/12805 is trying to acquire lock:
(&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<ffffffff81463361>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816
but task is already holding lock:
(ashmem_mutex){+.+.+.}, at: [<ffffffff82c62016>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
[<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
[<ffffffff8376a39b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
[<ffffffff8376a39b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
[<ffffffff82c61463>] ashmem_mmap+0x53/0x400 drivers/staging/android/ashmem.c:366
[<ffffffff814b0e4f>] mmap_region+0x94f/0x1250 mm/mmap.c:1664
[<ffffffff814b1c4d>] do_mmap+0x4fd/0x9d0 mm/mmap.c:1441
[<ffffffff814700ce>] do_mmap_pgoff include/linux/mm.h:1915 [inline]
[<ffffffff814700ce>] vm_mmap_pgoff+0x16e/0x1c0 mm/util.c:296
[<ffffffff814afe1f>] SYSC_mmap_pgoff mm/mmap.c:1491 [inline]
[<ffffffff814afe1f>] SyS_mmap_pgoff+0x33f/0x560 mm/mmap.c:1449
[<ffffffff8101beb6>] SYSC_mmap arch/x86/kernel/sys_x86_64.c:95 [inline]
[<ffffffff8101beb6>] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:86
[<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
[<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
[<ffffffff814956ea>] __might_fault+0x14a/0x1d0 mm/memory.c:3810
[<ffffffff8155ab22>] copy_to_user arch/x86/include/asm/uaccess.h:760 [inline]
[<ffffffff8155ab22>] filldir+0x162/0x2d0 fs/readdir.c:180
[<ffffffff8159820e>] dir_emit_dot include/linux/fs.h:3070 [inline]
[<ffffffff8159820e>] dir_emit_dots include/linux/fs.h:3081 [inline]
[<ffffffff8159820e>] dcache_readdir+0x11e/0x7b0 fs/libfs.c:150
[<ffffffff8155a768>] iterate_dir+0x1c8/0x420 fs/readdir.c:42
[<ffffffff8155b45a>] SYSC_getdents fs/readdir.c:215 [inline]
[<ffffffff8155b45a>] SyS_getdents+0x14a/0x270 fs/readdir.c:196
[<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
[<ffffffff8123ab2f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
[<ffffffff8123ab2f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
[<ffffffff8123ab2f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
[<ffffffff8123ab2f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
[<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
[<ffffffff8376a39b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
[<ffffffff8376a39b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
[<ffffffff81463361>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816
[<ffffffff8151c762>] vfs_llseek+0xa2/0xd0 fs/read_write.c:260
[<ffffffff82c620a7>] ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:342
[<ffffffff8151e56b>] vfs_llseek fs/read_write.c:260 [inline]
[<ffffffff8151e56b>] SYSC_lseek fs/read_write.c:285 [inline]
[<ffffffff8151e56b>] SyS_lseek+0xeb/0x170 fs/read_write.c:276
[<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
other info that might help us debug this:
Chain exists of:
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-executor0/12805:
#0: (ashmem_mutex){+.+.+.}, at: [<ffffffff82c62016>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330
stack backtrace:
CPU: 0 PID: 12805 Comm: syz-executor0 Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
0000000000000000 9d6ebf98f816db04 ffff8801d7867ad8 ffffffff81d0408d
ffffffff851a0010 ffffffff851a9d00 ffffffff851be7c0 ffff8801c1b7b8f8
ffff8801c1b7b000 ffff8801d7867b20 ffffffff81233ba1 ffff8801c1b7b8f8
Call Trace:
[<ffffffff81d0408d>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81d0408d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
[<ffffffff81233ba1>] print_circular_bug+0x271/0x310 kernel/locking/lockdep.c:1226
[<ffffffff8123ab2f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
[<ffffffff8123ab2f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
[<ffffffff8123ab2f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
[<ffffffff8123ab2f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
[<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
[<ffffffff8376a39b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
[<ffffffff8376a39b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
[<ffffffff81463361>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816
[<ffffffff8151c762>] vfs_llseek+0xa2/0xd0 fs/read_write.c:260
[<ffffffff82c620a7>] ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:342
[<ffffffff8151e56b>] vfs_llseek fs/read_write.c:260 [inline]
[<ffffffff8151e56b>] SYSC_lseek fs/read_write.c:285 [inline]
[<ffffffff8151e56b>] SyS_lseek+0xeb/0x170 fs/read_write.c:276
[<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
IPVS: Creating netns size=2552 id=31
IPVS: Creating netns size=2552 id=32
pktgen: kernel_thread() failed for cpu 0
pktgen: Cannot create thread for cpu 0 (-4)
pktgen: kernel_thread() failed for cpu 1
pktgen: Cannot create thread for cpu 1 (-4)
pktgen: Initialization failed for all threads
pktgen: kernel_thread() failed for cpu 0
pktgen: Cannot create thread for cpu 0 (-4)
IPVS: Creating netns size=2552 id=33
IPVS: Creating netns size=2552 id=34
audit: type=1400 audit(1521682375.978:30): avc: denied { dyntransition } for pid=13524 comm="syz-executor0" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0,c1 tclass=process permissive=1
IPVS: Creating netns size=2552 id=35