[openib-general] [kDAPL][PATCH] fix panic in server side

[Tom Duffy]

This occurred when I did a connect without first setting up a listen
using kdapltest. 

Unable to handle kernel NULL pointer dereference at 0000000000000020 RIP:
<ffffffff882b2c61>{:ib_dat_provider:dapl_cm_passive_cb_handler+27}
PGD 371ab067 PUD 36822067 PMD 0
Oops: 0000 [1] SMP
CPU 2
Modules linked in: kdapltest ib_dat_provider dat ib_at ib_cm ib_ipoib ib_sa ib_umad md5 ipv6 parport_pc lp parport autofs4 nfs lockd sunrpc pcmcia yenta_socket rsrc_nonstatic pcmcia_core ext3 jbd video container button battery ac uhci_hcd ehci_hcd hw_random i2c_i801 i2c_core ib_mthca ib_mad ib_core e1000 floppy dm_snapshot dm_zero dm_mirror xfs exportfs dm_mod mptscsih mptbase sd_mod scsi_mod
Pid: 11326, comm: ib_cm/2 Not tainted 2.6.12-rc3openib
RIP: 0010:[<ffffffff882b2c61>] <ffffffff882b2c61>{:ib_dat_provider:dapl_cm_passive_cb_handler+27}
RSP: 0018:ffff810038f65d90  EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff81000b3764b0 RCX: ffff81000b376550
RDX: 0000000000000056 RSI: ffff81000b376548 RDI: ffff81003f0cd8a0
RBP: ffff81003f0cd8a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000020 R11: ffff81003925ae10 R12: ffff81003f0cd8a0
R13: ffff81003dcb8a88 R14: 0000000000000000 R15: ffff81000b3765a0
FS:  0000000000000000(0000) GS:ffffffff80487a00(0000) knlGS:0000000000000000
CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 0000000000000020 CR3: 0000000038bbd000 CR4: 00000000000006e0
Process ib_cm/2 (pid: 11326, threadinfo ffff810038f64000, task ffff81003e75af30)Stack: ffffffff882aae32 0100000000000293 0000000000000000 ffff81000b3764b0
       000000003f0cd8a0 ffff81003dcb8a88 0000000000000000 ffff81000b3765a0
       ffffffff882abd1e ffff810001e1b680
Call Trace:<ffffffff882aae32>{:ib_cm:cm_process_work+50} <ffffffff882abd1e>{:ib_cm:cm_work_handler+1438}
       <ffffffff801435f8>{do_sigaction+520} <ffffffff882ab780>{:ib_cm:cm_work_handler+0}
       <ffffffff801489ac>{worker_thread+476} <ffffffff801321c0>{default_wake_function+0}
       <ffffffff80130283>{__wake_up_common+67} <ffffffff801487d0>{worker_thread+0}
       <ffffffff8014cfe0>{keventd_create_kthread+0} <ffffffff8014d259>{kthread+217}
       <ffffffff801336d0>{schedule_tail+64} <ffffffff8010f57b>{child_rip+8}
       <ffffffff8014cfe0>{keventd_create_kthread+0} <ffffffff8014d180>{kthread+0}
       <ffffffff8010f573>{child_rip+0}

Code: 8b 40 20 89 44 24 04 83 7c 24 04 03 74 30 83 7c 24 04 03 77
RIP <ffffffff882b2c61>{:ib_dat_provider:dapl_cm_passive_cb_handler+27} RSP <ffff810038f65d90>
CR2: 0000000000000020

This cuteness happened in the kdapltest userland program:

Warning: conn_event_wait DAT_CONNECTION_EVENT_DISCONNECTED
DT_cs_Client: bad connection event
DT_cs_Client: Cleaning Up ...
DT_cs_Client: IA mthca0a closed
DT_cs_Client: ========== End of Work -- Client Exiting
TEST INSTANCE 1
*** glibc detected *** free(): invalid next size (fast): 0x000000000050ca50 ***
Aborted (core dumped)

This patches fixes two things.  It makes it so that
dapl_cm_passive_cb_handler won't dereference a potentially NULL ib_cm_id
and also that it returns ret instead of 0 all the time.

Signed-off-by: Tom Duffy <tduffy at sun.com>

Index: dapl_openib_cm.c
===================================================================
--- linux-kernel/dat-provider/dapl_openib_cm.c	(revision 2257)
+++ linux-kernel/dat-provider/dapl_openib_cm.c	(working copy)
@@ -227,6 +227,9 @@ int dapl_cm_passive_cb_handler(struct ib
 {
 	int ret = 0;
 
+	if (!comm_id)
+		return -1;
+
 	switch (comm_id->state) {
 	case IB_CM_IDLE:
 		ret = do_passive_idle(comm_id);
@@ -247,7 +250,7 @@ int dapl_cm_passive_cb_handler(struct ib
 		break;
 	}
 
-	return 0;
+	return ret;
 }
 
 static void dapl_ib_destroy_cm_id_work(void *data)