syzbot

urandom_read: 2 callbacks suppressed
random: sshd: uninitialized urandom read (32 bytes read)
audit: type=1400 audit(1572771949.516:7): avc:  denied  { map } for  pid=1771 comm="syz-executor465" path="/root/syz-executor465108009" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
=============================
WARNING: suspicious RCU usage
4.14.151+ #0 Not tainted
-----------------------------
./include/linux/radix-tree.h:238 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor465/1771:
 #0:  (&sb->s_type->i_mutex_key#10){+.+.}, at: [<        (ptrval)>] inode_lock include/linux/fs.h:724 [inline]
 #0:  (&sb->s_type->i_mutex_key#10){+.+.}, at: [<        (ptrval)>] shmem_add_seals+0x12b/0xf80 mm/shmem.c:2831
 #1:  (&(&mapping->tree_lock)->rlock){-...}, at: [<        (ptrval)>] spin_lock_irq include/linux/spinlock.h:342 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){-...}, at: [<        (ptrval)>] shmem_tag_pins mm/shmem.c:2685 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){-...}, at: [<        (ptrval)>] shmem_wait_for_pins mm/shmem.c:2726 [inline]
 #1:  (&(&mapping->tree_lock)->rlock){-...}, at: [<        (ptrval)>] shmem_add_seals+0x2e1/0xf80 mm/shmem.c:2843

stack backtrace:
CPU: 0 PID: 1771 Comm: syz-executor465 Not tainted 4.14.151+ #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 radix_tree_deref_slot include/linux/radix-tree.h:238 [inline]
 shmem_tag_pins mm/shmem.c:2687 [inline]
 shmem_wait_for_pins mm/shmem.c:2726 [inline]
 shmem_add_seals+0x9d2/0xf80 mm/shmem.c:2843
 shmem_fcntl+0xea/0x120 mm/shmem.c:2878
 do_fcntl+0x5c8/0xd20 fs/fcntl.c:421
 SYSC_fcntl fs/fcntl.c:463 [inline]
 SyS_fcntl+0xc6/0x100 fs/fcntl.c:448
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4401b9
RSP: 002b:00007ffeb659a198 EFLAGS: 00000246 ORIG_RAX: 0000000000000048
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401b9
RDX: 0000000000000009 RSI: 0000000000000409 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a40