On Mon, Jul 27, 2020 at 6:53 PM Greg KH <gre...@linuxfoundation.org> wrote: > > On Mon, Jul 27, 2020 at 06:40:57PM +0530, B K Karthik wrote: > > fix a general protection fault in tipc_conn_delete_sub > > by checking for the existance of con->server. > > prevent a null-ptr-deref by returning -EINVAL when > > con->server is NULL > > > > general protection fault, probably for non-canonical address > > 0xdffffc0000000014: 0000 [#1] PREEMPT SMP KASAN > > KASAN: null-ptr-deref in range [0x00000000000000a0-0x00000000000000a7] > > CPU: 1 PID: 113 Comm: kworker/u4:3 Not tainted 5.6.0-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > Google 01/01/2011 > > Workqueue: tipc_send tipc_conn_send_work > > RIP: 0010:tipc_conn_delete_sub+0x54/0x440 net/tipc/topsrv.c:231 > > Code: 48 c1 ea 03 80 3c 02 00 0f 85 f0 03 00 00 48 b8 00 00 00 00 00 fc ff > > df 48 8b 6b 18 48 8d bd a0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f > > 85 c0 03 00 00 48 c7 c0 34 0b 8a 8a 4c 8b a5 a0 00 > > RSP: 0018:ffffc900012d7b58 EFLAGS: 00010206 > > RAX: dffffc0000000000 RBX: ffff8880a8269c00 RCX: ffffffff8789ca01 > > RDX: 0000000000000014 RSI: ffffffff8789a059 RDI: 00000000000000a0 > > RBP: 0000000000000000 R08: ffff8880a8d88380 R09: fffffbfff18577a8 > > R10: fffffbfff18577a7 R11: ffffffff8c2bbd3f R12: dffffc0000000000 > > R13: ffff888093d35a18 R14: ffff8880a8269c00 R15: ffff888093d35a00 > > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 000000000076c000 CR3: 000000009441d000 CR4: 00000000001406e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > tipc_conn_send_to_sock+0x380/0x560 net/tipc/topsrv.c:266 > > tipc_conn_send_work+0x6f/0x90 net/tipc/topsrv.c:304 > > process_one_work+0x965/0x16a0 kernel/workqueue.c:2266 > > worker_thread+0x96/0xe20 kernel/workqueue.c:2412 > > kthread+0x388/0x470 kernel/kthread.c:268 > > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > Modules linked in: > > ---[ end trace 2c161a84be832606 ]--- > > RIP: 0010:tipc_conn_delete_sub+0x54/0x440 net/tipc/topsrv.c:231 > > Code: 48 c1 ea 03 80 3c 02 00 0f 85 f0 03 00 00 48 b8 00 00 00 00 00 fc ff > > df 48 8b 6b 18 48 8d bd a0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f > > 85 c0 03 00 00 48 c7 c0 34 0b 8a 8a 4c 8b a5 a0 00 > > RSP: 0018:ffffc900012d7b58 EFLAGS: 00010206 > > RAX: dffffc0000000000 RBX: ffff8880a8269c00 RCX: ffffffff8789ca01 > > RDX: 0000000000000014 RSI: ffffffff8789a059 RDI: 00000000000000a0 > > RBP: 0000000000000000 R08: ffff8880a8d88380 R09: fffffbfff18577a8 > > R10: fffffbfff18577a7 R11: ffffffff8c2bbd3f R12: dffffc0000000000 > > R13: ffff888093d35a18 R14: ffff8880a8269c00 R15: ffff888093d35a00 > > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000020800000 CR3: 0000000091b8e000 CR4: 00000000001406e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > Reported-and-tested-by: > > syzbot+55a38037455d0351e...@syzkaller.appspotmail.com > > Signed-off-by: B K Karthik <bkkart...@pesu.pes.edu> > > --- > > net/tipc/topsrv.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c > > index 1489cfb941d8..6c8d0c6bb112 100644 > > --- a/net/tipc/topsrv.c > > +++ b/net/tipc/topsrv.c > > @@ -255,6 +255,9 @@ static void tipc_conn_send_to_sock(struct tipc_conn > > *con) > > int count = 0; > > int ret; > > > > + if (!con->server) > > + return -EINVAL; > > What is wrong with looking at the srv local variable instead? > > And how is server getting set to NULL and this function still being > called?
tipc_conn_send_work makes a call to connected() which just returns con && test_bit(CF_CONNECTED, &con->flags) maybe we can add this check to the implementation of connection() if you agree, but I found this solution to be fairly simpler because I'm not sure where else connected() is being used, and I did not want to introduce redundant function calls. Yes we can replace con->server with the local variable srv. Extremely sorry, I hadn't noticed it earlier. please let me know if i've wrongly understood any of these. thanks, karthik
