linux-stable.git/drivers/scsi, branch v4.9.282 Linux kernel stable tree scsi: core: Avoid printing an error if target_alloc() returns -ENXIO 2021-08-26T12:37:26+00:00 Sreekanth Reddy sreekanth.reddy@broadcom.com 2021-07-26T11:54:02+00:00 869d9b41d4c8c7bb412c56e02a0e873141fe6c48 [ Upstream commit 70edd2e6f652f67d854981fd67f9ad0f1deaea92 ] Avoid printing a 'target allocation failed' error if the driver target_alloc() callback function returns -ENXIO. This return value indicates that the corresponding H:C:T:L entry is empty. Removing this error reduces the scan time if the user issues SCAN_WILD_CARD scan operation through sysfs parameter on a host with a lot of empty H:C:T:L entries. Avoiding the printk on -ENXIO matches the behavior of the other callback functions during scanning. Link: https://lore.kernel.org/r/20210726115402.1936-1-sreekanth.reddy@broadcom.com Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 70edd2e6f652f67d854981fd67f9ad0f1deaea92 ]

Avoid printing a 'target allocation failed' error if the driver
target_alloc() callback function returns -ENXIO. This return value
indicates that the corresponding H:C:T:L entry is empty.

Removing this error reduces the scan time if the user issues SCAN_WILD_CARD
scan operation through sysfs parameter on a host with a lot of empty
H:C:T:L entries.

Avoiding the printk on -ENXIO matches the behavior of the other callback
functions during scanning.

Link: https://lore.kernel.org/r/20210726115402.1936-1-sreekanth.reddy@broadcom.com
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: scsi_dh_rdac: Avoid crash during rdac_bus_attach() 2021-08-26T12:37:26+00:00 Ye Bin yebin10@huawei.com 2021-01-13T06:31:03+00:00 110fde2fb2d3940953b5332a9c7ca296f9b9cd75 [ Upstream commit bc546c0c9abb3bb2fb46866b3d1e6ade9695a5f6 ] The following BUG_ON() was observed during RDAC scan: [595952.944297] kernel BUG at drivers/scsi/device_handler/scsi_dh_rdac.c:427! [595952.951143] Internal error: Oops - BUG: 0 [#1] SMP ...... [595953.251065] Call trace: [595953.259054] check_ownership+0xb0/0x118 [595953.269794] rdac_bus_attach+0x1f0/0x4b0 [595953.273787] scsi_dh_handler_attach+0x3c/0xe8 [595953.278211] scsi_dh_add_device+0xc4/0xe8 [595953.282291] scsi_sysfs_add_sdev+0x8c/0x2a8 [595953.286544] scsi_probe_and_add_lun+0x9fc/0xd00 [595953.291142] __scsi_scan_target+0x598/0x630 [595953.295395] scsi_scan_target+0x120/0x130 [595953.299481] fc_user_scan+0x1a0/0x1c0 [scsi_transport_fc] [595953.304944] store_scan+0xb0/0x108 [595953.308420] dev_attr_store+0x44/0x60 [595953.312160] sysfs_kf_write+0x58/0x80 [595953.315893] kernfs_fop_write+0xe8/0x1f0 [595953.319888] __vfs_write+0x60/0x190 [595953.323448] vfs_write+0xac/0x1c0 [595953.326836] ksys_write+0x74/0xf0 [595953.330221] __arm64_sys_write+0x24/0x30 Code is in check_ownership: list_for_each_entry_rcu(tmp, &h->ctlr->dh_list, node) { /* h->sdev should always be valid */ BUG_ON(!tmp->sdev); tmp->sdev->access_state = access_state; } rdac_bus_attach initialize_controller list_add_rcu(&h->node, &h->ctlr->dh_list); h->sdev = sdev; rdac_bus_detach list_del_rcu(&h->node); h->sdev = NULL; Fix the race between rdac_bus_attach() and rdac_bus_detach() where h->sdev is NULL when processing the RDAC attach. Link: https://lore.kernel.org/r/20210113063103.2698953-1-yebin10@huawei.com Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ye Bin <yebin10@huawei.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit bc546c0c9abb3bb2fb46866b3d1e6ade9695a5f6 ]

The following BUG_ON() was observed during RDAC scan:

[595952.944297] kernel BUG at drivers/scsi/device_handler/scsi_dh_rdac.c:427!
[595952.951143] Internal error: Oops - BUG: 0 [#1] SMP
......
[595953.251065] Call trace:
[595953.259054]  check_ownership+0xb0/0x118
[595953.269794]  rdac_bus_attach+0x1f0/0x4b0
[595953.273787]  scsi_dh_handler_attach+0x3c/0xe8
[595953.278211]  scsi_dh_add_device+0xc4/0xe8
[595953.282291]  scsi_sysfs_add_sdev+0x8c/0x2a8
[595953.286544]  scsi_probe_and_add_lun+0x9fc/0xd00
[595953.291142]  __scsi_scan_target+0x598/0x630
[595953.295395]  scsi_scan_target+0x120/0x130
[595953.299481]  fc_user_scan+0x1a0/0x1c0 [scsi_transport_fc]
[595953.304944]  store_scan+0xb0/0x108
[595953.308420]  dev_attr_store+0x44/0x60
[595953.312160]  sysfs_kf_write+0x58/0x80
[595953.315893]  kernfs_fop_write+0xe8/0x1f0
[595953.319888]  __vfs_write+0x60/0x190
[595953.323448]  vfs_write+0xac/0x1c0
[595953.326836]  ksys_write+0x74/0xf0
[595953.330221]  __arm64_sys_write+0x24/0x30

Code is in check_ownership:

	list_for_each_entry_rcu(tmp, &h->ctlr->dh_list, node) {
		/* h->sdev should always be valid */
		BUG_ON(!tmp->sdev);
		tmp->sdev->access_state = access_state;
	}

	rdac_bus_attach
		initialize_controller
			list_add_rcu(&h->node, &h->ctlr->dh_list);
			h->sdev = sdev;

	rdac_bus_detach
		list_del_rcu(&h->node);
		h->sdev = NULL;

Fix the race between rdac_bus_attach() and rdac_bus_detach() where h->sdev
is NULL when processing the RDAC attach.

Link: https://lore.kernel.org/r/20210113063103.2698953-1-yebin10@huawei.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: megaraid_mm: Fix end of loop tests for list_for_each_entry() 2021-08-26T12:37:26+00:00 Harshvardhan Jha harshvardhan.jha@oracle.com 2021-07-08T07:46:42+00:00 881dff363d838118047f135fed77f8ffa396e2ad [ Upstream commit 77541f78eadfe9fdb018a7b8b69f0f2af2cf4b82 ] The list_for_each_entry() iterator, "adapter" in this code, can never be NULL. If we exit the loop without finding the correct adapter then "adapter" points invalid memory that is an offset from the list head. This will eventually lead to memory corruption and presumably a kernel crash. Link: https://lore.kernel.org/r/20210708074642.23599-1-harshvardhan.jha@oracle.com Acked-by: Sumit Saxena <sumit.saxena@broadcom.com> Signed-off-by: Harshvardhan Jha <harshvardhan.jha@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 77541f78eadfe9fdb018a7b8b69f0f2af2cf4b82 ]

The list_for_each_entry() iterator, "adapter" in this code, can never be
NULL.  If we exit the loop without finding the correct adapter then
"adapter" points invalid memory that is an offset from the list head.  This
will eventually lead to memory corruption and presumably a kernel crash.

Link: https://lore.kernel.org/r/20210708074642.23599-1-harshvardhan.jha@oracle.com
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Harshvardhan Jha <harshvardhan.jha@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: sr: Return correct event when media event code is 3 2021-08-15T11:01:01+00:00 Li Manyi limanyi@uniontech.com 2021-07-26T11:49:13+00:00 c5831fbf4402bf59d35aa92082177f2edfbb0879 [ Upstream commit 5c04243a56a7977185b00400e59ca7e108004faf ] Media event code 3 is defined in the MMC-6 spec as follows: "MediaRemoval: The media has been removed from the specified slot, and the Drive is unable to access the media without user intervention. This applies to media changers only." This indicated that treating the condition as an EJECT_REQUEST was appropriate. However, doing so had the unfortunate side-effect of causing the drive tray to be physically ejected on resume. Instead treat the event as a MEDIA_CHANGE request. Fixes: 7dd753ca59d6 ("scsi: sr: Return appropriate error code when disk is ejected") Link: https://bugzilla.kernel.org/show_bug.cgi?id=213759 Link: https://lore.kernel.org/r/20210726114913.6760-1-limanyi@uniontech.com Signed-off-by: Li Manyi <limanyi@uniontech.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 5c04243a56a7977185b00400e59ca7e108004faf ]

Media event code 3 is defined in the MMC-6 spec as follows:

  "MediaRemoval: The media has been removed from the specified slot, and
   the Drive is unable to access the media without user intervention. This
   applies to media changers only."

This indicated that treating the condition as an EJECT_REQUEST was
appropriate. However, doing so had the unfortunate side-effect of causing
the drive tray to be physically ejected on resume. Instead treat the event
as a MEDIA_CHANGE request.

Fixes: 7dd753ca59d6 ("scsi: sr: Return appropriate error code when disk is ejected")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213759
Link: https://lore.kernel.org/r/20210726114913.6760-1-limanyi@uniontech.com
Signed-off-by: Li Manyi <limanyi@uniontech.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: iscsi: Fix iface sysfs attr detection 2021-07-28T07:14:27+00:00 Mike Christie michael.christie@oracle.com 2021-07-01T00:25:59+00:00 016c8b8eac3520b1a2c8dad2e707aef9f6b267de [ Upstream commit e746f3451ec7f91dcc9fd67a631239c715850a34 ] A ISCSI_IFACE_PARAM can have the same value as a ISCSI_NET_PARAM so when iscsi_iface_attr_is_visible tries to figure out the type by just checking the value, we can collide and return the wrong type. When we call into the driver we might not match and return that we don't want attr visible in sysfs. The patch fixes this by setting the type when we figure out what the param is. Link: https://lore.kernel.org/r/20210701002559.89533-1-michael.christie@oracle.com Fixes: 3e0f65b34cc9 ("[SCSI] iscsi_transport: Additional parameters for network settings") Signed-off-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e746f3451ec7f91dcc9fd67a631239c715850a34 ]

A ISCSI_IFACE_PARAM can have the same value as a ISCSI_NET_PARAM so when
iscsi_iface_attr_is_visible tries to figure out the type by just checking
the value, we can collide and return the wrong type. When we call into the
driver we might not match and return that we don't want attr visible in
sysfs. The patch fixes this by setting the type when we figure out what the
param is.

Link: https://lore.kernel.org/r/20210701002559.89533-1-michael.christie@oracle.com
Fixes: 3e0f65b34cc9 ("[SCSI] iscsi_transport: Additional parameters for network settings")
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: aic7xxx: Fix unintentional sign extension issue on left shift of u8 2021-07-28T07:14:25+00:00 Colin Ian King colin.king@canonical.com 2021-06-21T15:17:27+00:00 c1245d5c0deda935a50d89cd1f30b035a636198c [ Upstream commit 332a9dd1d86f1e7203fc7f0fd7e82f0b304200fe ] The shifting of the u8 integer returned fom ahc_inb(ahc, port+3) by 24 bits to the left will be promoted to a 32 bit signed int and then sign-extended to a u64. In the event that the top bit of the u8 is set then all then all the upper 32 bits of the u64 end up as also being set because of the sign-extension. Fix this by casting the u8 values to a u64 before the 24 bit left shift. [ This dates back to 2002, I found the offending commit from the git history git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git, commit f58eb66c0b0a ("Update aic7xxx driver to 6.2.10...") ] Link: https://lore.kernel.org/r/20210621151727.20667-1-colin.king@canonical.com Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Addresses-Coverity: ("Unintended sign extension") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 332a9dd1d86f1e7203fc7f0fd7e82f0b304200fe ]

The shifting of the u8 integer returned fom ahc_inb(ahc, port+3) by 24 bits
to the left will be promoted to a 32 bit signed int and then sign-extended
to a u64. In the event that the top bit of the u8 is set then all then all
the upper 32 bits of the u64 end up as also being set because of the
sign-extension. Fix this by casting the u8 values to a u64 before the 24
bit left shift.

[ This dates back to 2002, I found the offending commit from the git
history git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git,
commit f58eb66c0b0a ("Update aic7xxx driver to 6.2.10...") ]

Link: https://lore.kernel.org/r/20210621151727.20667-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Addresses-Coverity: ("Unintended sign extension")
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: be2iscsi: Fix an error handling path in beiscsi_dev_probe() 2021-07-20T14:21:15+00:00 Christophe JAILLET christophe.jaillet@wanadoo.fr 2021-06-12T07:18:34+00:00 63ebf10616e8cf58598dcd649787b8507b0ed150 [ Upstream commit 030e4138d11fced3b831c2761e4cecf347bae99c ] If an error occurs after a pci_enable_pcie_error_reporting() call, it must be undone by a corresponding pci_disable_pcie_error_reporting() call, as already done in the remove function. Link: https://lore.kernel.org/r/77adb02cfea7f1364e5603ecf3930d8597ae356e.1623482155.git.christophe.jaillet@wanadoo.fr Fixes: 3567f36a09d1 ("[SCSI] be2iscsi: Fix AER handling in driver") Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 030e4138d11fced3b831c2761e4cecf347bae99c ]

If an error occurs after a pci_enable_pcie_error_reporting() call, it must
be undone by a corresponding pci_disable_pcie_error_reporting() call, as
already done in the remove function.

Link: https://lore.kernel.org/r/77adb02cfea7f1364e5603ecf3930d8597ae356e.1623482155.git.christophe.jaillet@wanadoo.fr
Fixes: 3567f36a09d1 ("[SCSI] be2iscsi: Fix AER handling in driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: iscsi: Add iscsi_cls_conn refcount helpers 2021-07-20T14:21:11+00:00 Mike Christie michael.christie@oracle.com 2021-05-25T18:18:03+00:00 83bd5f16b16755787f85db8c8639958df8076417 [ Upstream commit b1d19e8c92cfb0ded180ef3376c20e130414e067 ] There are a couple places where we could free the iscsi_cls_conn while it's still in use. This adds some helpers to get/put a refcount on the struct and converts an exiting user. Subsequent commits will then use the helpers to fix 2 bugs in the eh code. Link: https://lore.kernel.org/r/20210525181821.7617-11-michael.christie@oracle.com Reviewed-by: Lee Duncan <lduncan@suse.com> Signed-off-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit b1d19e8c92cfb0ded180ef3376c20e130414e067 ]

There are a couple places where we could free the iscsi_cls_conn while it's
still in use. This adds some helpers to get/put a refcount on the struct
and converts an exiting user. Subsequent commits will then use the helpers
to fix 2 bugs in the eh code.

Link: https://lore.kernel.org/r/20210525181821.7617-11-michael.christie@oracle.com
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: lpfc: Fix "Unexpected timeout" error in direct attach topology 2021-07-20T14:21:11+00:00 James Smart jsmart2021@gmail.com 2021-05-14T19:55:51+00:00 a622c5ad9c73c7cce7d445586fb8734fca3ecc77 [ Upstream commit e30d55137edef47434c40d7570276a0846fe922c ] An 'unexpected timeout' message may be seen in a point-2-point topology. The message occurs when a PLOGI is received before the driver is notified of FLOGI completion. The FLOGI completion failure causes discovery to be triggered for a second time. The discovery timer is restarted but no new discovery activity is initiated, thus the timeout message eventually appears. In point-2-point, when discovery has progressed before the FLOGI completion is processed, it is not a failure. Add code to FLOGI completion to detect that discovery has progressed and exit the FLOGI handling (noop'ing it). Link: https://lore.kernel.org/r/20210514195559.119853-4-jsmart2021@gmail.com Co-developed-by: Justin Tee <justin.tee@broadcom.com> Signed-off-by: Justin Tee <justin.tee@broadcom.com> Signed-off-by: James Smart <jsmart2021@gmail.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e30d55137edef47434c40d7570276a0846fe922c ]

An 'unexpected timeout' message may be seen in a point-2-point topology.
The message occurs when a PLOGI is received before the driver is notified
of FLOGI completion. The FLOGI completion failure causes discovery to be
triggered for a second time. The discovery timer is restarted but no new
discovery activity is initiated, thus the timeout message eventually
appears.

In point-2-point, when discovery has progressed before the FLOGI completion
is processed, it is not a failure. Add code to FLOGI completion to detect
that discovery has progressed and exit the FLOGI handling (noop'ing it).

Link: https://lore.kernel.org/r/20210514195559.119853-4-jsmart2021@gmail.com
Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: core: Fix bad pointer dereference when ehandler kthread is invalid 2021-07-20T14:21:10+00:00 Tyrel Datwyler tyreld@linux.ibm.com 2021-07-01T19:56:59+00:00 d2f0b960d07e52bb664471b4de0ed8b08c636b3a commit 93aa71ad7379900e61c8adff6a710a4c18c7c99b upstream. Commit 66a834d09293 ("scsi: core: Fix error handling of scsi_host_alloc()") changed the allocation logic to call put_device() to perform host cleanup with the assumption that IDA removal and stopping the kthread would properly be performed in scsi_host_dev_release(). However, in the unlikely case that the error handler thread fails to spawn, shost->ehandler is set to ERR_PTR(-ENOMEM). The error handler cleanup code in scsi_host_dev_release() will call kthread_stop() if shost->ehandler != NULL which will always be the case whether the kthread was successfully spawned or not. In the case that it failed to spawn this has the nasty side effect of trying to dereference an invalid pointer when kthread_stop() is called. The following splat provides an example of this behavior in the wild: scsi host11: error handler thread failed to spawn, error = -4 Kernel attempted to read user page (10c) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on read at 0x0000010c Faulting instruction address: 0xc00000000818e9a8 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: ibmvscsi(+) scsi_transport_srp dm_multipath dm_mirror dm_region hash dm_log dm_mod fuse overlay squashfs loop CPU: 12 PID: 274 Comm: systemd-udevd Not tainted 5.13.0-rc7 #1 NIP: c00000000818e9a8 LR: c0000000089846e8 CTR: 0000000000007ee8 REGS: c000000037d12ea0 TRAP: 0300 Not tainted (5.13.0-rc7) MSR: 800000000280b033 &lt;SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE&gt; CR: 28228228 XER: 20040001 CFAR: c0000000089846e4 DAR: 000000000000010c DSISR: 40000000 IRQMASK: 0 GPR00: c0000000089846e8 c000000037d13140 c000000009cc1100 fffffffffffffffc GPR04: 0000000000000001 0000000000000000 0000000000000000 c000000037dc0000 GPR08: 0000000000000000 c000000037dc0000 0000000000000001 00000000fffff7ff GPR12: 0000000000008000 c00000000a049000 c000000037d13d00 000000011134d5a0 GPR16: 0000000000001740 c0080000190d0000 c0080000190d1740 c000000009129288 GPR20: c000000037d13bc0 0000000000000001 c000000037d13bc0 c0080000190b7898 GPR24: c0080000190b7708 0000000000000000 c000000033bb2c48 0000000000000000 GPR28: c000000046b28280 0000000000000000 000000000000010c fffffffffffffffc NIP [c00000000818e9a8] kthread_stop+0x38/0x230 LR [c0000000089846e8] scsi_host_dev_release+0x98/0x160 Call Trace: [c000000033bb2c48] 0xc000000033bb2c48 (unreliable) [c0000000089846e8] scsi_host_dev_release+0x98/0x160 [c00000000891e960] device_release+0x60/0x100 [c0000000087e55c4] kobject_release+0x84/0x210 [c00000000891ec78] put_device+0x28/0x40 [c000000008984ea4] scsi_host_alloc+0x314/0x430 [c0080000190b38bc] ibmvscsi_probe+0x54/0xad0 [ibmvscsi] [c000000008110104] vio_bus_probe+0xa4/0x4b0 [c00000000892a860] really_probe+0x140/0x680 [c00000000892aefc] driver_probe_device+0x15c/0x200 [c00000000892b63c] device_driver_attach+0xcc/0xe0 [c00000000892b740] __driver_attach+0xf0/0x200 [c000000008926f28] bus_for_each_dev+0xa8/0x130 [c000000008929ce4] driver_attach+0x34/0x50 [c000000008928fc0] bus_add_driver+0x1b0/0x300 [c00000000892c798] driver_register+0x98/0x1a0 [c00000000810eb60] __vio_register_driver+0x80/0xe0 [c0080000190b4a30] ibmvscsi_module_init+0x9c/0xdc [ibmvscsi] [c0000000080121d0] do_one_initcall+0x60/0x2d0 [c000000008261abc] do_init_module+0x7c/0x320 [c000000008265700] load_module+0x2350/0x25b0 [c000000008265cb4] __do_sys_finit_module+0xd4/0x160 [c000000008031110] system_call_exception+0x150/0x2d0 [c00000000800d35c] system_call_common+0xec/0x278 Fix this be nulling shost->ehandler when the kthread fails to spawn. Link: https://lore.kernel.org/r/20210701195659.3185475-1-tyreld@linux.ibm.com Fixes: 66a834d09293 ("scsi: core: Fix error handling of scsi_host_alloc()") Cc: stable@vger.kernel.org Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 93aa71ad7379900e61c8adff6a710a4c18c7c99b upstream.

Commit 66a834d09293 ("scsi: core: Fix error handling of scsi_host_alloc()")
changed the allocation logic to call put_device() to perform host cleanup
with the assumption that IDA removal and stopping the kthread would
properly be performed in scsi_host_dev_release(). However, in the unlikely
case that the error handler thread fails to spawn, shost->ehandler is set
to ERR_PTR(-ENOMEM).

The error handler cleanup code in scsi_host_dev_release() will call
kthread_stop() if shost->ehandler != NULL which will always be the case
whether the kthread was successfully spawned or not. In the case that it
failed to spawn this has the nasty side effect of trying to dereference an
invalid pointer when kthread_stop() is called. The following splat provides
an example of this behavior in the wild:

scsi host11: error handler thread failed to spawn, error = -4
Kernel attempted to read user page (10c) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x0000010c
Faulting instruction address: 0xc00000000818e9a8
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: ibmvscsi(+) scsi_transport_srp dm_multipath dm_mirror dm_region
 hash dm_log dm_mod fuse overlay squashfs loop
CPU: 12 PID: 274 Comm: systemd-udevd Not tainted 5.13.0-rc7 #1
NIP:  c00000000818e9a8 LR: c0000000089846e8 CTR: 0000000000007ee8
REGS: c000000037d12ea0 TRAP: 0300   Not tainted  (5.13.0-rc7)
MSR:  800000000280b033 &lt;SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE&gt;  CR: 28228228
XER: 20040001
CFAR: c0000000089846e4 DAR: 000000000000010c DSISR: 40000000 IRQMASK: 0
GPR00: c0000000089846e8 c000000037d13140 c000000009cc1100 fffffffffffffffc
GPR04: 0000000000000001 0000000000000000 0000000000000000 c000000037dc0000
GPR08: 0000000000000000 c000000037dc0000 0000000000000001 00000000fffff7ff
GPR12: 0000000000008000 c00000000a049000 c000000037d13d00 000000011134d5a0
GPR16: 0000000000001740 c0080000190d0000 c0080000190d1740 c000000009129288
GPR20: c000000037d13bc0 0000000000000001 c000000037d13bc0 c0080000190b7898
GPR24: c0080000190b7708 0000000000000000 c000000033bb2c48 0000000000000000
GPR28: c000000046b28280 0000000000000000 000000000000010c fffffffffffffffc
NIP [c00000000818e9a8] kthread_stop+0x38/0x230
LR [c0000000089846e8] scsi_host_dev_release+0x98/0x160
Call Trace:
[c000000033bb2c48] 0xc000000033bb2c48 (unreliable)
[c0000000089846e8] scsi_host_dev_release+0x98/0x160
[c00000000891e960] device_release+0x60/0x100
[c0000000087e55c4] kobject_release+0x84/0x210
[c00000000891ec78] put_device+0x28/0x40
[c000000008984ea4] scsi_host_alloc+0x314/0x430
[c0080000190b38bc] ibmvscsi_probe+0x54/0xad0 [ibmvscsi]
[c000000008110104] vio_bus_probe+0xa4/0x4b0
[c00000000892a860] really_probe+0x140/0x680
[c00000000892aefc] driver_probe_device+0x15c/0x200
[c00000000892b63c] device_driver_attach+0xcc/0xe0
[c00000000892b740] __driver_attach+0xf0/0x200
[c000000008926f28] bus_for_each_dev+0xa8/0x130
[c000000008929ce4] driver_attach+0x34/0x50
[c000000008928fc0] bus_add_driver+0x1b0/0x300
[c00000000892c798] driver_register+0x98/0x1a0
[c00000000810eb60] __vio_register_driver+0x80/0xe0
[c0080000190b4a30] ibmvscsi_module_init+0x9c/0xdc [ibmvscsi]
[c0000000080121d0] do_one_initcall+0x60/0x2d0
[c000000008261abc] do_init_module+0x7c/0x320
[c000000008265700] load_module+0x2350/0x25b0
[c000000008265cb4] __do_sys_finit_module+0xd4/0x160
[c000000008031110] system_call_exception+0x150/0x2d0
[c00000000800d35c] system_call_common+0xec/0x278

Fix this be nulling shost->ehandler when the kthread fails to spawn.

Link: https://lore.kernel.org/r/20210701195659.3185475-1-tyreld@linux.ibm.com
Fixes: 66a834d09293 ("scsi: core: Fix error handling of scsi_host_alloc()")
Cc: stable@vger.kernel.org
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>