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

[James Lentini]

Tom,

There were two changes in this patch:

- check for a NULL comm_id pointer
- add error returns

My understanding of the subsequent discussion is that:

- we should not have been using the comm_id->state value. We should
   have been using the event->event value instead

- if we return a non 0 error code, our CM ID will be destroyed

Given those pieces of information:

Do we still want to check for a NULL comm_id pointer?
Should we always return 0 from this function?

I think the answer is yes to both of the above, but I want to make 
sure there is consensus.

james

On Wed, 4 May 2005, Tom Duffy wrote:

> 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)
>