On Thu, Feb 1, 2018 at 11:22 PM, Eric Biggers <ebigge...@gmail.com> wrote: > On Sun, Dec 31, 2017 at 10:58:01AM -0800, syzbot wrote: >> Hello, >> >> syzkaller hit the following crash on >> 5aa90a84589282b87666f92b6c3c917c8080a9bf >> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master >> compiler: gcc (GCC) 7.1.1 20170620 >> .config is attached >> Raw console output is attached. >> C reproducer is attached >> syzkaller reproducer is attached. See https://goo.gl/kgGztJ >> for information about syzkaller reproducers >> >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+6345fd433db009b29...@syzkaller.appspotmail.com >> It will help syzbot understand when the bug is fixed. See footer for >> details. >> If you forward the report, please keep this part and the footer. >> >> audit: type=1400 audit(1514679888.244:9): avc: denied { write } for >> pid=3194 comm="syzkaller021477" path="socket:[11143]" dev="sockfs" ino=11143 >> scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 >> tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 >> tclass=netlink_generic_socket permissive=1 >> ============================= >> WARNING: suspicious RCU usage >> 4.15.0-rc5+ #152 Not tainted >> ----------------------------- >> net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage! >> >> other info that might help us debug this: >> >> >> rcu_scheduler_active = 2, debug_locks = 1 >> 2 locks held by syzkaller021477/3194: >> #0: (cb_lock){++++}, at: [<00000000d20133ea>] genl_rcv+0x19/0x40 >> net/netlink/genetlink.c:634 >> #1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_lock >> net/netlink/genetlink.c:33 [inline] >> #1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_rcv_msg+0x115/0x140 >> net/netlink/genetlink.c:622 >> >> stack backtrace: >> CPU: 1 PID: 3194 Comm: syzkaller021477 Not tainted 4.15.0-rc5+ #152 >> 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+0x194/0x257 lib/dump_stack.c:53 >> lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585 >> tipc_bearer_find+0x2b4/0x3b0 net/tipc/bearer.c:177 >> tipc_nl_compat_link_set+0x329/0x9f0 net/tipc/netlink_compat.c:729 >> __tipc_nl_compat_doit net/tipc/netlink_compat.c:288 [inline] >> tipc_nl_compat_doit+0x15b/0x660 net/tipc/netlink_compat.c:335 >> tipc_nl_compat_handle net/tipc/netlink_compat.c:1119 [inline] >> tipc_nl_compat_recv+0x112f/0x18f0 net/tipc/netlink_compat.c:1201 >> genl_family_rcv_msg+0x7b7/0xfb0 net/netlink/genetlink.c:599 >> genl_rcv_msg+0xb2/0x140 net/netlink/genetlink.c:624 >> netlink_rcv_skb+0x21e/0x460 net/netlink/af_netlink.c:2408 >> genl_rcv+0x28/0x40 net/netlink/genetlink.c:635 >> netlink_unicast_kernel net/netlink/af_netlink.c:1275 [inline] >> netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1301 >> netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1864 >> sock_sendmsg_nosec net/socket.c:636 [inline] >> sock_sendmsg+0xca/0x110 net/socket.c:646 >> sock_write_iter+0x31a/0x5d0 net/socket.c:915 >> call_write_iter include/linux/fs.h:1772 [inline] >> new_sync_write fs/read_write.c:469 [inline] >> __vfs_write+0x684/0x970 fs/read_write.c:482 >> vfs_write+0x189/0x510 fs/read_write.c:544 >> SYSC_write fs/read_write.c:589 [inline] >> SyS_write+0xef/0x220 fs/read_write.c:581 >> do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] >> do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 >> entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129 >> > > This is still happening; looks like a missing lock in > tipc_nl_compat_link_set(). > Note that the reproducer isn't guaranteed to work as-is because the message it > sends to the netlink socket assumes that the "TIPC" generic netlink family was > assigned ID 31, when actually it is a dynamically assigned ID. But it will > trigger if you adjust the message's ->nlmsg_type accordingly.
#syz dup: WARNING: suspicious RCU usage in tipc_bearer_find