linux-sg2042/drivers
Anoob Soman 79edd00dc6 scsi: libiscsi: Fix race between iscsi_xmit_task and iscsi_complete_task
When a target sends Check Condition, whilst initiator is busy xmiting
re-queued data, could lead to race between iscsi_complete_task() and
iscsi_xmit_task() and eventually crashing with the following kernel
backtrace.

[3326150.987523] ALERT: BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
[3326150.987549] ALERT: IP: [<ffffffffa05ce70d>] iscsi_xmit_task+0x2d/0xc0 [libiscsi]
[3326150.987571] WARN: PGD 569c8067 PUD 569c9067 PMD 0
[3326150.987582] WARN: Oops: 0002 [#1] SMP
[3326150.987593] WARN: Modules linked in: tun nfsv3 nfs fscache dm_round_robin
[3326150.987762] WARN: CPU: 2 PID: 8399 Comm: kworker/u32:1 Tainted: G O 4.4.0+2 #1
[3326150.987774] WARN: Hardware name: Dell Inc. PowerEdge R720/0W7JN5, BIOS 2.5.4 01/22/2016
[3326150.987790] WARN: Workqueue: iscsi_q_13 iscsi_xmitworker [libiscsi]
[3326150.987799] WARN: task: ffff8801d50f3800 ti: ffff8801f5458000 task.ti: ffff8801f5458000
[3326150.987810] WARN: RIP: e030:[<ffffffffa05ce70d>] [<ffffffffa05ce70d>] iscsi_xmit_task+0x2d/0xc0 [libiscsi]
[3326150.987825] WARN: RSP: e02b:ffff8801f545bdb0 EFLAGS: 00010246
[3326150.987831] WARN: RAX: 00000000ffffffc3 RBX: ffff880282d2ab20 RCX: ffff88026b6ac480
[3326150.987842] WARN: RDX: 0000000000000000 RSI: 00000000fffffe01 RDI: ffff880282d2ab20
[3326150.987852] WARN: RBP: ffff8801f545bdc8 R08: 0000000000000000 R09: 0000000000000008
[3326150.987862] WARN: R10: 0000000000000000 R11: 000000000000fe88 R12: 0000000000000000
[3326150.987872] WARN: R13: ffff880282d2abe8 R14: ffff880282d2abd8 R15: ffff880282d2ac08
[3326150.987890] WARN: FS: 00007f5a866b4840(0000) GS:ffff88028a640000(0000) knlGS:0000000000000000
[3326150.987900] WARN: CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033
[3326150.987907] WARN: CR2: 0000000000000078 CR3: 0000000070244000 CR4: 0000000000042660
[3326150.987918] WARN: Stack:
[3326150.987924] WARN: ffff880282d2ad58 ffff880282d2ab20 ffff880282d2abe8 ffff8801f545be18
[3326150.987938] WARN: ffffffffa05cea90 ffff880282d2abf8 ffff88026b59cc80 ffff88026b59cc00
[3326150.987951] WARN: ffff88022acf32c0 ffff880289491800 ffff880255a80800 0000000000000400
[3326150.987964] WARN: Call Trace:
[3326150.987975] WARN: [<ffffffffa05cea90>] iscsi_xmitworker+0x2f0/0x360 [libiscsi]
[3326150.987988] WARN: [<ffffffff8108862c>] process_one_work+0x1fc/0x3b0
[3326150.987997] WARN: [<ffffffff81088f95>] worker_thread+0x2a5/0x470
[3326150.988006] WARN: [<ffffffff8159cad8>] ? __schedule+0x648/0x870
[3326150.988015] WARN: [<ffffffff81088cf0>] ? rescuer_thread+0x300/0x300
[3326150.988023] WARN: [<ffffffff8108ddf5>] kthread+0xd5/0xe0
[3326150.988031] WARN: [<ffffffff8108dd20>] ? kthread_stop+0x110/0x110
[3326150.988040] WARN: [<ffffffff815a0bcf>] ret_from_fork+0x3f/0x70
[3326150.988048] WARN: [<ffffffff8108dd20>] ? kthread_stop+0x110/0x110
[3326150.988127] ALERT: RIP [<ffffffffa05ce70d>] iscsi_xmit_task+0x2d/0xc0 [libiscsi]
[3326150.988138] WARN: RSP <ffff8801f545bdb0>
[3326150.988144] WARN: CR2: 0000000000000078
[3326151.020366] WARN: ---[ end trace 1c60974d4678d81b ]---

Commit 6f8830f5bb ("scsi: libiscsi: add lock around task lists to fix
list corruption regression") introduced "taskqueuelock" to fix list
corruption during the race, but this wasn't enough.

Re-setting of conn->task to NULL, could race with iscsi_xmit_task().
iscsi_complete_task()
{
    ....
    if (conn->task == task)
        conn->task = NULL;
}

conn->task in iscsi_xmit_task() could be NULL and so will be task.
__iscsi_get_task(task) will crash (NullPtr de-ref), trying to access
refcount.

iscsi_xmit_task()
{
    struct iscsi_task *task = conn->task;

    __iscsi_get_task(task);
}

This commit will take extra conn->session->back_lock in iscsi_xmit_task()
to ensure iscsi_xmit_task() waits for iscsi_complete_task(), if
iscsi_complete_task() wins the race.  If iscsi_xmit_task() wins the race,
iscsi_xmit_task() increments task->refcount
(__iscsi_get_task) ensuring iscsi_complete_task() will not iscsi_free_task().

Signed-off-by: Anoob Soman <anoob.soman@citrix.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Acked-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-02-15 22:05:04 -05:00
..
accessibility
acpi Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
amba
android binder: implement binderfs 2018-12-19 09:40:13 +01:00
ata scsi: communicate max segment size to the DMA mapping code 2019-01-22 20:40:59 -05:00
atm
auxdisplay auxdisplay: charlcd: fix x/y command parsing 2018-12-21 21:27:21 +01:00
base Merge branch 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-01-05 13:25:58 -08:00
bcma
block block: sunvdc: don't run hw queue synchronously from irq context 2019-01-03 08:21:47 -07:00
bluetooth Bluetooth: hci_bcm: Handle specific unknown packets after firmware loading 2018-12-19 13:43:42 +01:00
bus ARM: SoC driver updates 2018-12-31 17:32:35 -08:00
cdrom gdrom: fix a memory leak bug 2018-12-29 08:20:44 -07:00
char Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
clk Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2019-01-02 18:56:59 -08:00
clocksource arch/csky patches for 4.21-rc1 2019-01-05 09:50:07 -08:00
connector
cpufreq powerpc updates for 4.21 2018-12-27 10:43:24 -08:00
cpuidle powerpc updates for 4.21 2018-12-27 10:43:24 -08:00
crypto Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
dax mm, devm_memremap_pages: fix shutdown handling 2018-12-28 12:11:47 -08:00
dca
devfreq
dio
dma Merge branch 'next/drivers' into next/late 2019-01-04 14:31:38 -08:00
dma-buf drivers/dma-buf/udmabuf.c: convert to use vm_fault_t 2019-01-04 13:13:46 -08:00
edac EDAC, fsl_ddr: Add LS1021A to the list of supported hardware 2018-12-19 11:57:45 +01:00
eisa
extcon
firewire scsi: communicate max segment size to the DMA mapping code 2019-01-22 20:40:59 -05:00
firmware arm64 fixes for -rc1 2019-01-05 11:28:39 -08:00
fmc
fpga Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
fsi
gnss
gpio This is the bulk of GPIO changes for the v4.21 kernel series: 2018-12-28 20:00:21 -08:00
gpu drm i915 gvt, amdgpu, core fixes 2019-01-05 18:25:19 -08:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2019-01-05 17:53:40 -08:00
hsi
hv Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -08:00
hwmon Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
hwspinlock hwspinlock: fix return value check in stm32_hwspinlock_probe() 2019-01-03 11:42:10 -08:00
hwtracing intel_th: msu: Fix an off-by-one in attribute store 2018-12-19 20:21:06 +01:00
i2c Merge branch 'i2c/for-5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-01-05 18:13:35 -08:00
i3c
ide for-4.21/block-20181221 2018-12-28 13:19:59 -08:00
idle
iio Staging/IIO driver patches for 4.21-rc1 2018-12-28 20:39:58 -08:00
infiniband 4.21 merge window 2nd pull request 2019-01-05 18:20:51 -08:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2019-01-02 18:56:59 -08:00
iommu IOMMU Updates for Linux v4.21 2019-01-01 15:55:29 -08:00
ipack
irqchip Xtensa updates for v4.21: 2018-12-29 09:40:40 -08:00
isdn isdn: fix kernel-infoleak in capi_unlocked_ioctl 2019-01-02 10:31:39 -08:00
leds LEDs for 4.21-rc1 2018-12-25 14:52:50 -08:00
lightnvm lightnvm: pblk: fix use-after-free bug 2018-12-22 14:45:35 -07:00
macintosh Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
mailbox mailbox: tegra-hsp: Use device-managed registration API 2018-12-21 22:31:26 -06:00
mcb
md Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md into for-linus 2019-01-03 08:21:02 -07:00
media Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
memory ARM: SoC: late updates 2019-01-05 11:30:37 -08:00
memstick MMC core: 2018-12-28 16:52:18 -08:00
message scsi: flip the default on use_clustering 2018-12-18 23:13:12 -05:00
mfd
misc Merge branch 'i2c/for-5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-01-05 18:13:35 -08:00
mmc MMC core: 2018-12-28 16:52:18 -08:00
mtd Kbuild updates for v4.21 2018-12-29 12:03:17 -08:00
mux
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-03 12:53:47 -08:00
nfc
ntb
nubus
nvdimm Merge branch 'akpm' (patches from Andrew) 2018-12-28 16:55:46 -08:00
nvme nvme-pci: trace SQ status on completions 2018-12-19 08:35:36 +01:00
nvmem
of Merge tag 'devicetree-for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux 2018-12-28 20:08:34 -08:00
opp
oprofile
parisc Kconfig file consolidation for v4.21 2018-12-29 13:40:29 -08:00
parport
pci pci-v4.21-changes 2019-01-05 17:57:34 -08:00
pcmcia Included in this update: 2019-01-05 11:23:17 -08:00
perf drivers/perf: hisi: Fixup one DDRC PMU register offset 2019-01-04 10:13:27 +00:00
phy
pinctrl Pin control bulk changes for the v4.21 kernel cycle: 2019-01-01 13:19:16 -08:00
platform chrome platform changes for v4.21 2019-01-06 11:40:06 -08:00
pnp Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
power power supply and reset changes for the v4.21 series 2018-12-28 20:22:45 -08:00
powercap
pps Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
ps3
ptp Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -08:00
pwm pwm: imx: Add ipg clock operation 2018-12-24 12:06:56 +01:00
rapidio
ras treewide: surround Kconfig file paths with double quotes 2018-12-22 00:25:54 +09:00
regulator Merge remote-tracking branch 'regulator/topic/coupled' into regulator-next 2018-12-21 13:43:35 +00:00
remoteproc
reset
rpmsg
rtc RTC for 4.21 2019-01-01 13:24:31 -08:00
s390 scsi: zfcp: fix sysfs block queue limit output for max_segment_size 2019-01-29 01:14:59 -05:00
sbus Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next 2018-12-26 10:32:18 -08:00
scsi scsi: libiscsi: Fix race between iscsi_xmit_task and iscsi_complete_task 2019-02-15 22:05:04 -05:00
sfi
sh
siox
slimbus
sn
soc ARM: SoC driver updates 2018-12-31 17:32:35 -08:00
soundwire
spi spi: Updates for v4.21 2018-12-25 14:43:54 -08:00
spmi
ssb
staging Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
target scsi: target: make the pi_prot_format ConfigFS path readable 2019-02-04 21:40:32 -05:00
tc
tee OP-TEE dynamic shm log message 2018-12-31 13:06:30 -08:00
thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2019-01-05 16:07:28 -08:00
thunderbolt
tty ARM: SoC: late updates 2019-01-05 11:30:37 -08:00
uio Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -08:00
usb pci-v4.21-changes 2019-01-05 17:57:34 -08:00
uwb
vfio IOMMU Updates for Linux v4.21 2019-01-01 15:55:29 -08:00
vhost Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
video fbdev changes for v4.21: 2019-01-05 18:15:37 -08:00
virt
virtio virtio, vhost: features, fixes, cleanups 2019-01-02 18:54:45 -08:00
visorbus
vlynq
vme
w1 treewide: surround Kconfig file paths with double quotes 2018-12-22 00:25:54 +09:00
watchdog linux-watchdog 4.21-rc1 tag 2019-01-01 13:16:45 -08:00
xen Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
zorro
Kconfig Kconfig file consolidation for v4.21 2018-12-29 13:40:29 -08:00
Makefile