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author | Benjamin Block <bblock@linux.vnet.ibm.com> | 2016-12-09 17:16:31 +0100 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2016-12-14 15:14:04 -0500 |
commit | dac37e15b7d511e026a9313c8c46794c144103cd (patch) | |
tree | 1aac535ca7ab7a8931b12155499798b5635d7882 /drivers/s390/scsi | |
parent | 165ae50e450bc7de6c741bf2c27ed0920a40a9af (diff) | |
download | linux-stable-dac37e15b7d511e026a9313c8c46794c144103cd.tar.gz linux-stable-dac37e15b7d511e026a9313c8c46794c144103cd.tar.bz2 linux-stable-dac37e15b7d511e026a9313c8c46794c144103cd.zip |
scsi: zfcp: fix use-after-"free" in FC ingress path after TMF
When SCSI EH invokes zFCP's callbacks for eh_device_reset_handler() and
eh_target_reset_handler(), it expects us to relent the ownership over
the given scsi_cmnd and all other scsi_cmnds within the same scope - LUN
or target - when returning with SUCCESS from the callback ('release'
them). SCSI EH can then reuse those commands.
We did not follow this rule to release commands upon SUCCESS; and if
later a reply arrived for one of those supposed to be released commands,
we would still make use of the scsi_cmnd in our ingress tasklet. This
will at least result in undefined behavior or a kernel panic because of
a wrong kernel pointer dereference.
To fix this, we NULLify all pointers to scsi_cmnds (struct zfcp_fsf_req
*)->data in the matching scope if a TMF was successful. This is done
under the locks (struct zfcp_adapter *)->abort_lock and (struct
zfcp_reqlist *)->lock to prevent the requests from being removed from
the request-hashtable, and the ingress tasklet from making use of the
scsi_cmnd-pointer in zfcp_fsf_fcp_cmnd_handler().
For cases where a reply arrives during SCSI EH, but before we get a
chance to NULLify the pointer - but before we return from the callback
-, we assume that the code is protected from races via the CAS operation
in blk_complete_request() that is called in scsi_done().
The following stacktrace shows an example for a crash resulting from the
previous behavior:
Unable to handle kernel pointer dereference at virtual kernel address fffffee17a672000
Oops: 0038 [#1] SMP
CPU: 2 PID: 0 Comm: swapper/2 Not tainted
task: 00000003f7ff5be0 ti: 00000003f3d38000 task.ti: 00000003f3d38000
Krnl PSW : 0404d00180000000 00000000001156b0 (smp_vcpu_scheduled+0x18/0x40)
R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 EA:3
Krnl GPRS: 000000200000007e 0000000000000000 fffffee17a671fd8 0000000300000015
ffffffff80000000 00000000005dfde8 07000003f7f80e00 000000004fa4e800
000000036ce8d8f8 000000036ce8d9c0 00000003ece8fe00 ffffffff969c9e93
00000003fffffffd 000000036ce8da10 00000000003bf134 00000003f3b07918
Krnl Code: 00000000001156a2: a7190000 lghi %r1,0
00000000001156a6: a7380015 lhi %r3,21
#00000000001156aa: e32050000008 ag %r2,0(%r5)
>00000000001156b0: 482022b0 lh %r2,688(%r2)
00000000001156b4: ae123000 sigp %r1,%r2,0(%r3)
00000000001156b8: b2220020 ipm %r2
00000000001156bc: 8820001c srl %r2,28
00000000001156c0: c02700000001 xilf %r2,1
Call Trace:
([<0000000000000000>] 0x0)
[<000003ff807bdb8e>] zfcp_fsf_fcp_cmnd_handler+0x3de/0x490 [zfcp]
[<000003ff807be30a>] zfcp_fsf_req_complete+0x252/0x800 [zfcp]
[<000003ff807c0a48>] zfcp_fsf_reqid_check+0xe8/0x190 [zfcp]
[<000003ff807c194e>] zfcp_qdio_int_resp+0x66/0x188 [zfcp]
[<000003ff80440c64>] qdio_kick_handler+0xdc/0x310 [qdio]
[<000003ff804463d0>] __tiqdio_inbound_processing+0xf8/0xcd8 [qdio]
[<0000000000141fd4>] tasklet_action+0x9c/0x170
[<0000000000141550>] __do_softirq+0xe8/0x258
[<000000000010ce0a>] do_softirq+0xba/0xc0
[<000000000014187c>] irq_exit+0xc4/0xe8
[<000000000046b526>] do_IRQ+0x146/0x1d8
[<00000000005d6a3c>] io_return+0x0/0x8
[<00000000005d6422>] vtime_stop_cpu+0x4a/0xa0
([<0000000000000000>] 0x0)
[<0000000000103d8a>] arch_cpu_idle+0xa2/0xb0
[<0000000000197f94>] cpu_startup_entry+0x13c/0x1f8
[<0000000000114782>] smp_start_secondary+0xda/0xe8
[<00000000005d6efe>] restart_int_handler+0x56/0x6c
[<0000000000000000>] 0x0
Last Breaking-Event-Address:
[<00000000003bf12e>] arch_spin_lock_wait+0x56/0xb0
Suggested-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Fixes: ea127f9754 ("[PATCH] s390 (7/7): zfcp host adapter.") (tglx/history.git)
Cc: <stable@vger.kernel.org> #2.6.32+
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/s390/scsi')
-rw-r--r-- | drivers/s390/scsi/zfcp_dbf.h | 11 | ||||
-rw-r--r-- | drivers/s390/scsi/zfcp_reqlist.h | 30 | ||||
-rw-r--r-- | drivers/s390/scsi/zfcp_scsi.c | 57 |
3 files changed, 95 insertions, 3 deletions
diff --git a/drivers/s390/scsi/zfcp_dbf.h b/drivers/s390/scsi/zfcp_dbf.h index 36d07584271d..2d06b5d2c05b 100644 --- a/drivers/s390/scsi/zfcp_dbf.h +++ b/drivers/s390/scsi/zfcp_dbf.h @@ -388,4 +388,15 @@ void zfcp_dbf_scsi_devreset(char *tag, struct scsi_cmnd *scmnd, u8 flag) _zfcp_dbf_scsi(tmp_tag, 1, scmnd, NULL); } +/** + * zfcp_dbf_scsi_nullcmnd() - trace NULLify of SCSI command in dev/tgt-reset. + * @scmnd: SCSI command that was NULLified. + * @fsf_req: request that owned @scmnd. + */ +static inline void zfcp_dbf_scsi_nullcmnd(struct scsi_cmnd *scmnd, + struct zfcp_fsf_req *fsf_req) +{ + _zfcp_dbf_scsi("scfc__1", 3, scmnd, fsf_req); +} + #endif /* ZFCP_DBF_H */ diff --git a/drivers/s390/scsi/zfcp_reqlist.h b/drivers/s390/scsi/zfcp_reqlist.h index 7c2c6194dfca..703fce59befe 100644 --- a/drivers/s390/scsi/zfcp_reqlist.h +++ b/drivers/s390/scsi/zfcp_reqlist.h @@ -4,7 +4,7 @@ * Data structure and helper functions for tracking pending FSF * requests. * - * Copyright IBM Corp. 2009 + * Copyright IBM Corp. 2009, 2016 */ #ifndef ZFCP_REQLIST_H @@ -180,4 +180,32 @@ static inline void zfcp_reqlist_move(struct zfcp_reqlist *rl, spin_unlock_irqrestore(&rl->lock, flags); } +/** + * zfcp_reqlist_apply_for_all() - apply a function to every request. + * @rl: the requestlist that contains the target requests. + * @f: the function to apply to each request; the first parameter of the + * function will be the target-request; the second parameter is the same + * pointer as given with the argument @data. + * @data: freely chosen argument; passed through to @f as second parameter. + * + * Uses :c:macro:`list_for_each_entry` to iterate over the lists in the hash- + * table (not a 'safe' variant, so don't modify the list). + * + * Holds @rl->lock over the entire request-iteration. + */ +static inline void +zfcp_reqlist_apply_for_all(struct zfcp_reqlist *rl, + void (*f)(struct zfcp_fsf_req *, void *), void *data) +{ + struct zfcp_fsf_req *req; + unsigned long flags; + unsigned int i; + + spin_lock_irqsave(&rl->lock, flags); + for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++) + list_for_each_entry(req, &rl->buckets[i], list) + f(req, data); + spin_unlock_irqrestore(&rl->lock, flags); +} + #endif /* ZFCP_REQLIST_H */ diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c index 9069f98a1817..11cd18c134c1 100644 --- a/drivers/s390/scsi/zfcp_scsi.c +++ b/drivers/s390/scsi/zfcp_scsi.c @@ -3,7 +3,7 @@ * * Interface to Linux SCSI midlayer. * - * Copyright IBM Corp. 2002, 2015 + * Copyright IBM Corp. 2002, 2016 */ #define KMSG_COMPONENT "zfcp" @@ -209,6 +209,57 @@ static int zfcp_scsi_eh_abort_handler(struct scsi_cmnd *scpnt) return retval; } +struct zfcp_scsi_req_filter { + u8 tmf_scope; + u32 lun_handle; + u32 port_handle; +}; + +static void zfcp_scsi_forget_cmnd(struct zfcp_fsf_req *old_req, void *data) +{ + struct zfcp_scsi_req_filter *filter = + (struct zfcp_scsi_req_filter *)data; + + /* already aborted - prevent side-effects - or not a SCSI command */ + if (old_req->data == NULL || old_req->fsf_command != FSF_QTCB_FCP_CMND) + return; + + /* (tmf_scope == FCP_TMF_TGT_RESET || tmf_scope == FCP_TMF_LUN_RESET) */ + if (old_req->qtcb->header.port_handle != filter->port_handle) + return; + + if (filter->tmf_scope == FCP_TMF_LUN_RESET && + old_req->qtcb->header.lun_handle != filter->lun_handle) + return; + + zfcp_dbf_scsi_nullcmnd((struct scsi_cmnd *)old_req->data, old_req); + old_req->data = NULL; +} + +static void zfcp_scsi_forget_cmnds(struct zfcp_scsi_dev *zsdev, u8 tm_flags) +{ + struct zfcp_adapter *adapter = zsdev->port->adapter; + struct zfcp_scsi_req_filter filter = { + .tmf_scope = FCP_TMF_TGT_RESET, + .port_handle = zsdev->port->handle, + }; + unsigned long flags; + + if (tm_flags == FCP_TMF_LUN_RESET) { + filter.tmf_scope = FCP_TMF_LUN_RESET; + filter.lun_handle = zsdev->lun_handle; + } + + /* + * abort_lock secures against other processings - in the abort-function + * and normal cmnd-handler - of (struct zfcp_fsf_req *)->data + */ + write_lock_irqsave(&adapter->abort_lock, flags); + zfcp_reqlist_apply_for_all(adapter->req_list, zfcp_scsi_forget_cmnd, + &filter); + write_unlock_irqrestore(&adapter->abort_lock, flags); +} + static int zfcp_task_mgmt_function(struct scsi_cmnd *scpnt, u8 tm_flags) { struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(scpnt->device); @@ -241,8 +292,10 @@ static int zfcp_task_mgmt_function(struct scsi_cmnd *scpnt, u8 tm_flags) if (fsf_req->status & ZFCP_STATUS_FSFREQ_TMFUNCFAILED) { zfcp_dbf_scsi_devreset("fail", scpnt, tm_flags); retval = FAILED; - } else + } else { zfcp_dbf_scsi_devreset("okay", scpnt, tm_flags); + zfcp_scsi_forget_cmnds(zfcp_sdev, tm_flags); + } zfcp_fsf_req_free(fsf_req); return retval; |