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Subject[PATCH] mpt2sas: mpt3sas: Fix memory corruption during initialization
Date
While _scsih_probe_sas() is initializing devices, the hardware can trigger a
MPI2_EVENT_SAS_TOPO_RC_TARG_NOT_RESPONDING interrupt.

The handler for TARG_NOT_RESPONDING calls _scsih_device_remove_by_handle(),
which deletes the device in question from either ioc->sas_device_list or
ioc->sas_device_init_list. Since _scsih_probe_sas() uses no exclusion when
iterating over ioc->sas_device_init_list, this results in a use-after-free
in _scsih_probe_sas(), and also corrupts the list:

mpt2sas1: removing handle(0x0020), sas_addr(0x5f80f418573360e0)
mpt2sas1: log_info(0x31111000): originator(PL), code(0x11), sub_code(0x1000)
------------[ cut here ]------------
WARNING: at lib/list_debug.c:56 __list_del_entry+0xc3/0xd0()
list_del corruption, ffff88240012fa00->prev is LIST_POISON2 (dead000000200200)
<snip>
Workqueue: events work_for_cpu_fn
ffffffff810c4f17 ffff881214825b38 0000000000000009 ffff881214825ae8
ffffffff8169b61e ffff881214825b28 ffffffff8104a990 0000000000000002
ffff88240012f900 ffff88240012fa00 ffff881217595af8 0000000000000282
Call Trace:
[<ffffffff810c4f17>] ? print_modules+0xd7/0x120
[<ffffffff8169b61e>] dump_stack+0x19/0x1b
[<ffffffff8104a990>] warn_slowpath_common+0x70/0xa0
[<ffffffff8104aa76>] warn_slowpath_fmt+0x46/0x50
[<ffffffff816a2234>] ? _raw_spin_lock_irqsave+0x84/0xa0
[<ffffffffa0010e8e>] ? _scsih_probe_sas+0x8e/0x110 [mpt2sas]
[<ffffffff8132a5a3>] __list_del_entry+0xc3/0xd0
[<ffffffffa0010e99>] _scsih_probe_sas+0x99/0x110 [mpt2sas]
[<ffffffffa0011d5f>] _scsih_scan_finished+0x19f/0x2c0 [mpt2sas]
[<ffffffff81429d67>] do_scsi_scan_host+0x77/0xa0
[<ffffffff81429f20>] scsi_scan_host+0x190/0x1c0
[<ffffffffa0011402>] _scsih_probe+0x452/0x640 [mpt2sas]
[<ffffffff813444eb>] local_pci_probe+0x4b/0x80
[<ffffffff8106b848>] work_for_cpu_fn+0x18/0x30
[<ffffffff81070012>] process_one_work+0x212/0x6e0
[<ffffffff8106ffa6>] ? process_one_work+0x1a6/0x6e0
[<ffffffff8108ed1f>] ? local_clock+0x4f/0x60
[<ffffffff8107050c>] process_scheduled_works+0x2c/0x40
[<ffffffff81070ae2>] worker_thread+0x262/0x370
[<ffffffff81070880>] ? rescuer_thread+0x360/0x360
[<ffffffff81078f3b>] kthread+0xdb/0xe0
[<ffffffff810b5e8d>] ? trace_hardirqs_on+0xd/0x10
[<ffffffff81078e60>] ? kthread_create_on_node+0x140/0x140
[<ffffffff816ac01c>] ret_from_fork+0x7c/0xb0
[<ffffffff81078e60>] ? kthread_create_on_node+0x140/0x140
---[ end trace 41352a0bd2d0d61b ]---

This either results in an immediate panic, or corrupts random memory and
causes nasty problems later in the box's uptime.

This patch splices the discovered devices out of the global list while
holding the lock, since _scsih_probe_sas() always removes them from that
global list anyway (either deleting them if initialization fails, or
moving them onto ioc->sas_device_list if it succeeds). The interrupt that
caused this bug will no longer cause the device to be removed during
initialization, since it won't exist on the global lists, but
_scsih_probe_sas() will remove it anyway when it fails to initialize.

Cc: stable@vger.kernel.org
Signed-off-by: Calvin Owens <calvinowens@fb.com>
---
drivers/scsi/mpt2sas/mpt2sas_scsih.c | 14 +++++++++++---
drivers/scsi/mpt3sas/mpt3sas_scsih.c | 14 +++++++++++---
2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/mpt2sas/mpt2sas_scsih.c b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
index 3f26147..4d603cb 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_scsih.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
@@ -7977,11 +7977,19 @@ _scsih_probe_sas(struct MPT2SAS_ADAPTER *ioc)
{
struct _sas_device *sas_device, *next;
unsigned long flags;
+ LIST_HEAD(head);

- /* SAS Device List */
- list_for_each_entry_safe(sas_device, next, &ioc->sas_device_init_list,
- list) {
+ /*
+ * Yank the entries out of the global list before attempting to iterate
+ * over them, since interrupts can delete sas_device entries out of the
+ * global list while we iterate.
+ */
+ spin_lock_irqsave(&ioc->sas_device_lock, flags);
+ list_splice_init(&ioc->sas_device_init_list, &head);
+ spin_unlock_irqrestore(&ioc->sas_device_lock, flags);

+ /* SAS Device List */
+ list_for_each_entry_safe(sas_device, next, &head, list) {
if (ioc->hide_drives)
continue;

diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index 5a97e32..1a6a6a3 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -7609,11 +7609,19 @@ _scsih_probe_sas(struct MPT3SAS_ADAPTER *ioc)
{
struct _sas_device *sas_device, *next;
unsigned long flags;
+ LIST_HEAD(head);

- /* SAS Device List */
- list_for_each_entry_safe(sas_device, next, &ioc->sas_device_init_list,
- list) {
+ /*
+ * Yank the entries out of the global list before attempting to iterate
+ * over them, since interrupts can delete sas_device entries out of the
+ * global list while we iterate.
+ */
+ spin_lock_irqsave(&ioc->sas_device_lock, flags);
+ list_splice_init(&ioc->sas_device_init_list, &head);
+ spin_unlock_irqrestore(&ioc->sas_device_lock, flags);

+ /* SAS Device List */
+ list_for_each_entry_safe(sas_device, next, &head, list) {
if (!mpt3sas_transport_port_add(ioc, sas_device->handle,
sas_device->sas_address_parent)) {
list_del(&sas_device->list);
--
1.8.1


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