Hi Mike,

url:    
https://github.com/0day-ci/linux/commits/Mike-Christie/iscsi-fixes-and-cleanups/20210203-122757
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi.git for-next
config: i386-randconfig-m021-20210202 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
Reported-by: Dan Carpenter <[email protected]>

smatch warnings:
drivers/scsi/libiscsi_tcp.c:586 iscsi_tcp_r2t_rsp() warn: variable dereferenced 
before check 'task->sc' (see line 547)

vim +586 drivers/scsi/libiscsi_tcp.c

f7dbf0662a0167 Mike Christie     2021-02-02  529  static int 
iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
a081c13e39b5c1 Mike Christie     2008-12-02  530  {
a081c13e39b5c1 Mike Christie     2008-12-02  531        struct iscsi_session 
*session = conn->session;
f7dbf0662a0167 Mike Christie     2021-02-02  532        struct iscsi_tcp_task 
*tcp_task;
f7dbf0662a0167 Mike Christie     2021-02-02  533        struct iscsi_tcp_conn 
*tcp_conn;
f7dbf0662a0167 Mike Christie     2021-02-02  534        struct iscsi_r2t_rsp 
*rhdr;
a081c13e39b5c1 Mike Christie     2008-12-02  535        struct iscsi_r2t_info 
*r2t;
f7dbf0662a0167 Mike Christie     2021-02-02  536        struct iscsi_task *task;
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  537        u32 data_length;
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  538        u32 data_offset;
f7dbf0662a0167 Mike Christie     2021-02-02  539        int r2tsn;
a081c13e39b5c1 Mike Christie     2008-12-02  540        int rc;
a081c13e39b5c1 Mike Christie     2008-12-02  541  
f7dbf0662a0167 Mike Christie     2021-02-02  542        
spin_lock(&session->back_lock);
f7dbf0662a0167 Mike Christie     2021-02-02  543        task = 
iscsi_itt_to_ctask(conn, hdr->itt);
f7dbf0662a0167 Mike Christie     2021-02-02  544        if (!task) {
f7dbf0662a0167 Mike Christie     2021-02-02  545                
spin_unlock(&session->back_lock);
f7dbf0662a0167 Mike Christie     2021-02-02  546                return 
ISCSI_ERR_BAD_ITT;
f7dbf0662a0167 Mike Christie     2021-02-02 @547        } else if 
(task->sc->sc_data_direction != DMA_TO_DEVICE) {
                                                                   ^^^^^^^^
New unchecked dereference.

f7dbf0662a0167 Mike Christie     2021-02-02  548                
spin_unlock(&session->back_lock);
f7dbf0662a0167 Mike Christie     2021-02-02  549                return 
ISCSI_ERR_PROTO;
f7dbf0662a0167 Mike Christie     2021-02-02  550        }
f7dbf0662a0167 Mike Christie     2021-02-02  551        /*
f7dbf0662a0167 Mike Christie     2021-02-02  552         * A bad target might 
complete the cmd before we have handled R2Ts
f7dbf0662a0167 Mike Christie     2021-02-02  553         * so get a ref to the 
task that will be dropped in the xmit path.
f7dbf0662a0167 Mike Christie     2021-02-02  554         */
f7dbf0662a0167 Mike Christie     2021-02-02  555        if (task->state != 
ISCSI_TASK_RUNNING) {
f7dbf0662a0167 Mike Christie     2021-02-02  556                
spin_unlock(&session->back_lock);
f7dbf0662a0167 Mike Christie     2021-02-02  557                /* Let the path 
that got the early rsp complete it */
f7dbf0662a0167 Mike Christie     2021-02-02  558                return 0;
f7dbf0662a0167 Mike Christie     2021-02-02  559        }
f7dbf0662a0167 Mike Christie     2021-02-02  560        task->last_xfer = 
jiffies;
f7dbf0662a0167 Mike Christie     2021-02-02  561        __iscsi_get_task(task);
f7dbf0662a0167 Mike Christie     2021-02-02  562  
f7dbf0662a0167 Mike Christie     2021-02-02  563        tcp_conn = 
conn->dd_data;
f7dbf0662a0167 Mike Christie     2021-02-02  564        rhdr = (struct 
iscsi_r2t_rsp *)tcp_conn->in.hdr;
f7dbf0662a0167 Mike Christie     2021-02-02  565        /* fill-in new R2T 
associated with the task */
f7dbf0662a0167 Mike Christie     2021-02-02  566        
iscsi_update_cmdsn(session, (struct iscsi_nopin *)rhdr);
f7dbf0662a0167 Mike Christie     2021-02-02  567        
spin_unlock(&session->back_lock);
f7dbf0662a0167 Mike Christie     2021-02-02  568  
a081c13e39b5c1 Mike Christie     2008-12-02  569        if 
(tcp_conn->in.datalen) {
a081c13e39b5c1 Mike Christie     2008-12-02  570                
iscsi_conn_printk(KERN_ERR, conn,
a081c13e39b5c1 Mike Christie     2008-12-02  571                                
  "invalid R2t with datalen %d\n",
a081c13e39b5c1 Mike Christie     2008-12-02  572                                
  tcp_conn->in.datalen);
f7dbf0662a0167 Mike Christie     2021-02-02  573                rc = 
ISCSI_ERR_DATALEN;
f7dbf0662a0167 Mike Christie     2021-02-02  574                goto put_task;
a081c13e39b5c1 Mike Christie     2008-12-02  575        }
a081c13e39b5c1 Mike Christie     2008-12-02  576  
f7dbf0662a0167 Mike Christie     2021-02-02  577        tcp_task = 
task->dd_data;
f7dbf0662a0167 Mike Christie     2021-02-02  578        r2tsn = 
be32_to_cpu(rhdr->r2tsn);
a081c13e39b5c1 Mike Christie     2008-12-02  579        if 
(tcp_task->exp_datasn != r2tsn){
0ab1c2529e6a70 Mike Christie     2009-03-05  580                
ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
0ab1c2529e6a70 Mike Christie     2009-03-05  581                              
tcp_task->exp_datasn, r2tsn);
f7dbf0662a0167 Mike Christie     2021-02-02  582                rc = 
ISCSI_ERR_R2TSN;
f7dbf0662a0167 Mike Christie     2021-02-02  583                goto put_task;
a081c13e39b5c1 Mike Christie     2008-12-02  584        }
a081c13e39b5c1 Mike Christie     2008-12-02  585  
a081c13e39b5c1 Mike Christie     2008-12-02 @586        if (!task->sc || 
session->state != ISCSI_STATE_LOGGED_IN) {
                                                             ^^^^^^^^
Checked too late.

a081c13e39b5c1 Mike Christie     2008-12-02  587                
iscsi_conn_printk(KERN_INFO, conn,
a081c13e39b5c1 Mike Christie     2008-12-02  588                                
  "dropping R2T itt %d in recovery.\n",
a081c13e39b5c1 Mike Christie     2008-12-02  589                                
  task->itt);
f7dbf0662a0167 Mike Christie     2021-02-02  590                rc = 0;
f7dbf0662a0167 Mike Christie     2021-02-02  591                goto put_task;
a081c13e39b5c1 Mike Christie     2008-12-02  592        }
a081c13e39b5c1 Mike Christie     2008-12-02  593  
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  594        data_length = 
be32_to_cpu(rhdr->data_length);
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  595        if (data_length == 0) {
a081c13e39b5c1 Mike Christie     2008-12-02  596                
iscsi_conn_printk(KERN_ERR, conn,
a081c13e39b5c1 Mike Christie     2008-12-02  597                                
  "invalid R2T with zero data len\n");
f7dbf0662a0167 Mike Christie     2021-02-02  598                rc = 
ISCSI_ERR_DATALEN;
f7dbf0662a0167 Mike Christie     2021-02-02  599                goto put_task;
a081c13e39b5c1 Mike Christie     2008-12-02  600        }
a081c13e39b5c1 Mike Christie     2008-12-02  601  
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  602        if (data_length > 
session->max_burst)
0ab1c2529e6a70 Mike Christie     2009-03-05  603                
ISCSI_DBG_TCP(conn, "invalid R2T with data len %u and max "
0ab1c2529e6a70 Mike Christie     2009-03-05  604                              
"burst %u. Attempting to execute request.\n",
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  605                              
data_length, session->max_burst);
a081c13e39b5c1 Mike Christie     2008-12-02  606  
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  607        data_offset = 
be32_to_cpu(rhdr->data_offset);
ae3d56d81507c3 Christoph Hellwig 2019-01-29  608        if (data_offset + 
data_length > task->sc->sdb.length) {
a081c13e39b5c1 Mike Christie     2008-12-02  609                
iscsi_conn_printk(KERN_ERR, conn,
a081c13e39b5c1 Mike Christie     2008-12-02  610                                
  "invalid R2T with data len %u at offset %u "
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  611                                
  "and total length %d\n", data_length,
ae3d56d81507c3 Christoph Hellwig 2019-01-29  612                                
  data_offset, task->sc->sdb.length);
f7dbf0662a0167 Mike Christie     2021-02-02  613                rc = 
ISCSI_ERR_DATALEN;
f7dbf0662a0167 Mike Christie     2021-02-02  614                goto put_task;
a081c13e39b5c1 Mike Christie     2008-12-02  615        }
a081c13e39b5c1 Mike Christie     2008-12-02  616  
659743b02c4110 Shlomo Pongratz   2014-02-07  617        
spin_lock(&tcp_task->pool2queue);
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  618        rc = 
kfifo_out(&tcp_task->r2tpool.queue, (void *)&r2t, sizeof(void *));
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  619        if (!rc) {
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  620                
iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  621                                
  "Target has sent more R2Ts than it "
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  622                                
  "negotiated for or driver has leaked.\n");
659743b02c4110 Shlomo Pongratz   2014-02-07  623                
spin_unlock(&tcp_task->pool2queue);
f7dbf0662a0167 Mike Christie     2021-02-02  624                rc = 
ISCSI_ERR_PROTO;
f7dbf0662a0167 Mike Christie     2021-02-02  625                goto put_task;
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  626        }
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  627  
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  628        r2t->exp_statsn = 
rhdr->statsn;
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  629        r2t->data_length = 
data_length;
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  630        r2t->data_offset = 
data_offset;
5d0fddd0a72d30 Shlomo Pongratz   2014-02-07  631  
a081c13e39b5c1 Mike Christie     2008-12-02  632        r2t->ttt = rhdr->ttt; 
/* no flip */
a081c13e39b5c1 Mike Christie     2008-12-02  633        r2t->datasn = 0;
a081c13e39b5c1 Mike Christie     2008-12-02  634        r2t->sent = 0;
a081c13e39b5c1 Mike Christie     2008-12-02  635  
a081c13e39b5c1 Mike Christie     2008-12-02  636        tcp_task->exp_datasn = 
r2tsn + 1;
7acd72eb85f1c7 Stefani Seibold   2009-12-21  637        
kfifo_in(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
a081c13e39b5c1 Mike Christie     2008-12-02  638        conn->r2t_pdus_cnt++;
659743b02c4110 Shlomo Pongratz   2014-02-07  639        
spin_unlock(&tcp_task->pool2queue);
a081c13e39b5c1 Mike Christie     2008-12-02  640  
a081c13e39b5c1 Mike Christie     2008-12-02  641        
iscsi_requeue_task(task);
a081c13e39b5c1 Mike Christie     2008-12-02  642        return 0;
f7dbf0662a0167 Mike Christie     2021-02-02  643  
f7dbf0662a0167 Mike Christie     2021-02-02  644  put_task:
f7dbf0662a0167 Mike Christie     2021-02-02  645        iscsi_put_task(task);
f7dbf0662a0167 Mike Christie     2021-02-02  646        return rc;
a081c13e39b5c1 Mike Christie     2008-12-02  647  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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