答复: [PATCH] scsi: avoid potential deadloop in iscsi_if_rx func

2019-10-29 Thread wubo (T) 
On 2019/10/29 2:04, Lee Duncan wrote:
> On 10/26/19 1:55 AM, wubo (T) wrote:
>> From: Bo Wu 
>>
>> In iscsi_if_rx func, after receiving one request through 
>> iscsi_if_recv_msg func,iscsi_if_send_reply will be called to try to 
>> reply the request in do-loop. If the return of iscsi_if_send_reply 
>> func fails all the time, one deadloop will occur.
>>
>> Signed-off-by: Bo Wu 
>> Reviewed-by: Zhiqiang Liu 
>> ---
>>  drivers/scsi/scsi_transport_iscsi.c | 6 ++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/scsi/scsi_transport_iscsi.c 
>> b/drivers/scsi/scsi_transport_iscsi.c
>> index 417b868d8735..f377bfed6b0c 100644
>> --- a/drivers/scsi/scsi_transport_iscsi.c
>> +++ b/drivers/scsi/scsi_transport_iscsi.c
>> @@ -24,6 +24,8 @@
>>  
>>  #define ISCSI_TRANSPORT_VERSION "2.0-870"
>>  
>> +#define ISCSI_SEND_MAX_ALLOWED 10
>> +
>>  #define CREATE_TRACE_POINTS
>>  #include 
>>  
>> @@ -3682,6 +3684,7 @@ iscsi_if_rx(struct sk_buff *skb)
>>  struct nlmsghdr *nlh;
>>  struct iscsi_uevent *ev;
>>  uint32_t group;
>> +int retries = ISCSI_SEND_MAX_ALLOWED;
>>  
>>  nlh = nlmsg_hdr(skb);
>>  if (nlh->nlmsg_len < sizeof(*nlh) + sizeof(*ev) || @@ -3710,8 
>> +3713,11 @@ iscsi_if_rx(struct sk_buff *skb)
>>  break;
>>  if (ev->type == ISCSI_UEVENT_GET_CHAP && !err)
>>  break;
>> +if (retries <= 0)
>> +break;
>>  err = iscsi_if_send_reply(portid, nlh->nlmsg_type,
>>ev, sizeof(*ev));
>> +retries--;
>>  } while (err < 0 && err != -ECONNREFUSED && err != -ESRCH);
>>  skb_pull(skb, rlen);
>>  }
>>
> 
> You could have used "if (--retries < 0)" (or some variation thereof) 
> but that may not be as clear, and certainly is only a nit. So I'm fine 
> with that.
> 

Thanks for your suggestion, I will modify it in v2 patch.

> But I would like to see some sort of error or even debug kernel 
> message if we time out waiting to receive a response. Otherwise, how 
> will some human diagnose this problem?
>

You are right, I will add some sort of error or debug kernel message in the v2 
patch.

Thanks,
Bo Wu

-- 
You received this message because you are subscribed to the Google Groups 
"open-iscsi" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to open-iscsi+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/open-iscsi/EDBAAA0BBBA2AC4E9C8B6B81DEEE1D6915DF66B3%40dggeml505-mbs.china.huawei.com.

[PATCH] scsi: avoid potential deadloop in iscsi_if_rx func

2019-10-28 Thread wubo (T) 
From: Bo Wu 

In iscsi_if_rx func, after receiving one request through iscsi_if_recv_msg
func,iscsi_if_send_reply will be called to try to reply the request in 
do-loop. If the return of iscsi_if_send_reply func fails all the time, one
deadloop will occur.
 
For example, a client only send msg without calling recvmsg func, then it
will result in the watchdog soft lockup. The details are given as follows,

Details of the special case which can cause deadloop:
sock_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ISCSI); 
... 
retval = bind(sock_fd, (struct sock addr*) & src_addr, sizeof (src_addr); 
... 
while (1) { 
state_smg = sendmsg(sock_fd, , 0); 
} 
// Note: recvmsg (sock_fd, & msg, 0) is not processed here. 
close(sock_fd); 

watchdog: BUG: soft lockup - CPU#7 stuck for 22s! [netlink_test:253305]
Sample time: 4000897528 ns(HZ: 250)
Sample stat: 
curr: user: 675503481560, nice: 321724050, sys: 448689506750, idle: 
4654054240530, iowait: 40885550700, irq: 14161174020, softirq: 8104324140, st: 0
deta: user: 0, nice: 0, sys: 3998210100, idle: 0, iowait: 0, irq: 1547170, 
softirq: 242870, st: 0
Sample softirq:
TIMER:992
SCHED:  8
Sample irqstat:
 irq2: delta   1003, curr:3103802, arch_timer
CPU: 7 PID: 253305 Comm: netlink_test Kdump: loaded Tainted: G   OE 
Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
pstate: 4045 (nZcv daif +PAN -UAO)
pc : __alloc_skb+0x104/0x1b0
lr : __alloc_skb+0x9c/0x1b0
sp : 33603a30
x29: 33603a30 x28: 02dd 
x27: 800b34ced810 x26: 800ba7569f00 
x25:  x24:  
x23: 800f7c43f600 x22: 00480020 
x21: 091d9000 x20: 800b34eff200 
x19: 800ba7569f00 x18:  
x17:  x16:  
x15:  x14: 0001000101000100 
x13: 00010101 x12: 010101010100 
x11: 0001010101010001 x10: 02dd 
x9 : 33603d58 x8 : 800b34eff400 
x7 : 800ba7569200 x6 : 800b34eff400 
x5 :  x4 :  
x3 :  x2 : 0001 
x1 : 800b34eff2c0 x0 : 0300 
Call trace:
__alloc_skb+0x104/0x1b0
iscsi_if_rx+0x144/0x12bc [scsi_transport_iscsi]
netlink_unicast+0x1e0/0x258
netlink_sendmsg+0x310/0x378
sock_sendmsg+0x4c/0x70
sock_write_iter+0x90/0xf0
__vfs_write+0x11c/0x190
vfs_write+0xac/0x1c0
ksys_write+0x6c/0xd8
__arm64_sys_write+0x24/0x30
el0_svc_common+0x78/0x130
el0_svc_handler+0x38/0x78
el0_svc+0x8/0xc

Here, we add one limit of retry times in do-loop to avoid the deadloop.

Signed-off-by: Bo Wu 
Reviewed-by: Zhiqiang Liu 
---
 drivers/scsi/scsi_transport_iscsi.c | 6 ++
 1 file changed, 6 insertions(+)

diff --git a/drivers/scsi/scsi_transport_iscsi.c 
b/drivers/scsi/scsi_transport_iscsi.c
index 417b868d8735..f377bfed6b0c 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -24,6 +24,8 @@
 
 #define ISCSI_TRANSPORT_VERSION "2.0-870"
 
+#define ISCSI_SEND_MAX_ALLOWED 10
+
 #define CREATE_TRACE_POINTS
 #include 
 
@@ -3682,6 +3684,7 @@ iscsi_if_rx(struct sk_buff *skb)
struct nlmsghdr *nlh;
struct iscsi_uevent *ev;
uint32_t group;
+   int retries = ISCSI_SEND_MAX_ALLOWED;
 
nlh = nlmsg_hdr(skb);
if (nlh->nlmsg_len < sizeof(*nlh) + sizeof(*ev) ||
@@ -3710,8 +3713,11 @@ iscsi_if_rx(struct sk_buff *skb)
break;
if (ev->type == ISCSI_UEVENT_GET_CHAP && !err)
break;
+   if (retries <= 0)
+   break;
err = iscsi_if_send_reply(portid, nlh->nlmsg_type,
  ev, sizeof(*ev));
+   retries--;
} while (err < 0 && err != -ECONNREFUSED && err != -ESRCH);
skb_pull(skb, rlen);
}
-- 
1.8.3.1

-- 
You received this message because you are subscribed to the Google Groups 
"open-iscsi" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to open-iscsi+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/open-iscsi/EDBAAA0BBBA2AC4E9C8B6B81DEEE1D6915DE9E71%40DGGEML525-MBS.china.huawei.com.

Re: [PATCH] scsi: avoid potential deadloop in iscsi_if_rx func

2019-10-28 Thread Lee Duncan 
On 10/26/19 1:55 AM, wubo (T) wrote:
> From: Bo Wu 
> 
> In iscsi_if_rx func, after receiving one request through iscsi_if_recv_msg
> func,iscsi_if_send_reply will be called to try to reply the request in 
> do-loop. If the return of iscsi_if_send_reply func fails all the time, one
> deadloop will occur.
>  
> For example, a client only send msg without calling recvmsg func, then it
> will result in the watchdog soft lockup. The details are given as follows,
> 
> Details of the special case which can cause deadloop:
> sock_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ISCSI); 
> ... 
> retval = bind(sock_fd, (struct sock addr*) & src_addr, sizeof (src_addr); 
> ... 
> while (1) { 
>   state_smg = sendmsg(sock_fd, , 0); 
> } 
> // Note: recvmsg (sock_fd, & msg, 0) is not processed here. 
> close(sock_fd); 
> 
> watchdog: BUG: soft lockup - CPU#7 stuck for 22s! [netlink_test:253305]
> Sample time: 4000897528 ns(HZ: 250)
> Sample stat: 
> curr: user: 675503481560, nice: 321724050, sys: 448689506750, idle: 
> 4654054240530, iowait: 40885550700, irq: 14161174020, softirq: 8104324140, 
> st: 0
> deta: user: 0, nice: 0, sys: 3998210100, idle: 0, iowait: 0, irq: 1547170, 
> softirq: 242870, st: 0
> Sample softirq:
>   TIMER:992
>   SCHED:  8
> Sample irqstat:
>  irq2: delta   1003, curr:3103802, arch_timer
> CPU: 7 PID: 253305 Comm: netlink_test Kdump: loaded Tainted: G   OE   
>   
> Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
> pstate: 4045 (nZcv daif +PAN -UAO)
> pc : __alloc_skb+0x104/0x1b0
> lr : __alloc_skb+0x9c/0x1b0
> sp : 33603a30
> x29: 33603a30 x28: 02dd 
> x27: 800b34ced810 x26: 800ba7569f00 
> x25:  x24:  
> x23: 800f7c43f600 x22: 00480020 
> x21: 091d9000 x20: 800b34eff200 
> x19: 800ba7569f00 x18:  
> x17:  x16:  
> x15:  x14: 0001000101000100 
> x13: 00010101 x12: 010101010100 
> x11: 0001010101010001 x10: 02dd 
> x9 : 33603d58 x8 : 800b34eff400 
> x7 : 800ba7569200 x6 : 800b34eff400 
> x5 :  x4 :  
> x3 :  x2 : 0001 
> x1 : 800b34eff2c0 x0 : 0300 
> Call trace:
> __alloc_skb+0x104/0x1b0
> iscsi_if_rx+0x144/0x12bc [scsi_transport_iscsi]
> netlink_unicast+0x1e0/0x258
> netlink_sendmsg+0x310/0x378
> sock_sendmsg+0x4c/0x70
> sock_write_iter+0x90/0xf0
> __vfs_write+0x11c/0x190
> vfs_write+0xac/0x1c0
> ksys_write+0x6c/0xd8
> __arm64_sys_write+0x24/0x30
> el0_svc_common+0x78/0x130
> el0_svc_handler+0x38/0x78
> el0_svc+0x8/0xc
> 
> Here, we add one limit of retry times in do-loop to avoid the deadloop.
> 
> Signed-off-by: Bo Wu 
> Reviewed-by: Zhiqiang Liu 
> ---
>  drivers/scsi/scsi_transport_iscsi.c | 6 ++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_transport_iscsi.c 
> b/drivers/scsi/scsi_transport_iscsi.c
> index 417b868d8735..f377bfed6b0c 100644
> --- a/drivers/scsi/scsi_transport_iscsi.c
> +++ b/drivers/scsi/scsi_transport_iscsi.c
> @@ -24,6 +24,8 @@
>  
>  #define ISCSI_TRANSPORT_VERSION "2.0-870"
>  
> +#define ISCSI_SEND_MAX_ALLOWED 10
> +
>  #define CREATE_TRACE_POINTS
>  #include 
>  
> @@ -3682,6 +3684,7 @@ iscsi_if_rx(struct sk_buff *skb)
>   struct nlmsghdr *nlh;
>   struct iscsi_uevent *ev;
>   uint32_t group;
> + int retries = ISCSI_SEND_MAX_ALLOWED;
>  
>   nlh = nlmsg_hdr(skb);
>   if (nlh->nlmsg_len < sizeof(*nlh) + sizeof(*ev) ||
> @@ -3710,8 +3713,11 @@ iscsi_if_rx(struct sk_buff *skb)
>   break;
>   if (ev->type == ISCSI_UEVENT_GET_CHAP && !err)
>   break;
> + if (retries <= 0)
> + break;
>   err = iscsi_if_send_reply(portid, nlh->nlmsg_type,
> ev, sizeof(*ev));
> + retries--;
>   } while (err < 0 && err != -ECONNREFUSED && err != -ESRCH);
>   skb_pull(skb, rlen);
>   }
> 

You could have used "if (--retries < 0)" (or some variation thereof) but
that may not be as clear, and certainly is only a nit. So I'm fine with
that.

But I would like to see some sort of error or even debug kernel message
if we time out waiting to receive a response. Otherwise, how will some
human diagnose this problem?

-- 
Lee Duncan

-- 
You received this message because you are subscribed to the Google Groups 
"open-iscsi" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to open-iscsi+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/open-iscsi/92b221da-18a8-8b7b-0436-ca59088fd45b%40suse.com.