Re: [RFT PATCH] xhci: Fix memory leak when caching protocol extended capability PSI tables

[Marek Szyprowski <m.szyprowski@samsung.com>]

Hi

On 08.01.2020 16:17, Mathias Nyman wrote:
> xhci driver assumed that xHC controllers have at most one custom
> supported speed table (PSI) for all usb 3.x ports.
> Memory was allocated for one PSI table under the xhci hub structure.
>
> Turns out this is not the case, some controllers have a separate
> "supported protocol capability" entry with a PSI table for each port.
> This means each usb3 port can in theory support different custom speeds.
>
> To solve this cache all supported protocol capabilities with their PSI
> tables in an array, and add pointers to the xhci port structure so that
> every port points to its capability entry in the array.
>
> When creating the SuperSpeedPlus USB Device Capability BOS descriptor
> for the xhci USB 3.1 roothub we for now will use only data from the
> first USB 3.1 capable protocol capability entry in the array.
> This could be improved later, this patch focuses resolving
> the memory leak.
>
> Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
> Reported-by: Sajja Venkateswara Rao <VenkateswaraRao.Sajja@amd.com>
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>

This patch landed in today's linux-next (20200211) and causes NULL 
pointer dereference during second suspend/resume cycle on Samsung 
Exynos5422-based (arm 32bit) Odroid XU3lite board:

# time rtcwake -s10 -mmem
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Feb 11 10:51:43 2020
PM: suspend entry (deep)
Filesystems sync: 0.012 seconds
Freezing user space processes ... (elapsed 0.010 seconds) done.
OOM killer disabled.
Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done.
smsc95xx 1-1.1:1.0 eth0: entering SUSPEND2 mode
wake enabled for irq 153
wake enabled for irq 158
samsung-pinctrl 13400000.pinctrl: Setting external wakeup interrupt 
mask: 0xffffffe7
Disabling non-boot CPUs ...
IRQ 51: no longer affine to CPU1
IRQ 52: no longer affine to CPU2
s3c2410-wdt 101d0000.watchdog: watchdog disabled
wake disabled for irq 158
usb usb1: root hub lost power or was reset
usb usb2: root hub lost power or was reset
wake disabled for irq 153
exynos-tmu 10060000.tmu: More trip points than supported by this TMU.
exynos-tmu 10060000.tmu: 2 trip points should be configured in polling mode.
exynos-tmu 10064000.tmu: More trip points than supported by this TMU.
exynos-tmu 10064000.tmu: 2 trip points should be configured in polling mode.
exynos-tmu 10068000.tmu: More trip points than supported by this TMU.
exynos-tmu 10068000.tmu: 2 trip points should be configured in polling mode.
exynos-tmu 1006c000.tmu: More trip points than supported by this TMU.
exynos-tmu 1006c000.tmu: 2 trip points should be configured in polling mode.
exynos-tmu 100a0000.tmu: More trip points than supported by this TMU.
exynos-tmu 100a0000.tmu: 6 trip points should be configured in polling mode.
usb usb3: root hub lost power or was reset
s3c-rtc 101e0000.rtc: rtc disabled, re-enabling
usb usb4: root hub lost power or was reset
xhci-hcd xhci-hcd.8.auto: No ports on the roothubs?
PM: dpm_run_callback(): platform_pm_resume+0x0/0x44 returns -12
PM: Device xhci-hcd.8.auto failed to resume async: error -12
hub 3-0:1.0: hub_ext_port_status failed (err = -32)
hub 4-0:1.0: hub_ext_port_status failed (err = -32)
usb 1-1: reset high-speed USB device number 2 using exynos-ehci
usb 1-1.1: reset high-speed USB device number 3 using exynos-ehci
OOM killer enabled.
Restarting tasks ... done.

real    0m11.890s
user    0m0.001s
sys     0m0.679s
root@target:~# PM: suspend exit
mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 400000Hz, 
actual 396825HZ div = 63)
mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 200000000Hz, 
actual 200000000HZ div = 0)
mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 52000000Hz, 
actual 50000000HZ div = 0)
mmc_host mmc0: Bus speed (slot 0) = 400000000Hz (slot req 200000000Hz, 
actual 200000000HZ div = 1)
smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xC1E1

root@target:~#
root@target:~# time rtcwake -s10 -mmem[   35.451572] vdd_ldo12: disabling

rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Feb 11 10:52:02 2020
PM: suspend entry (deep)
Filesystems sync: 0.004 seconds
Freezing user space processes ... (elapsed 0.006 seconds) done.
OOM killer disabled.
Freezing remaining freezable tasks ... (elapsed 0.070 seconds) done.
hub 4-0:1.0: hub_ext_port_status failed (err = -32)
hub 3-0:1.0: hub_ext_port_status failed (err = -32)
8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 00000014
pgd = 4c26b54b
[00000014] *pgd=00000000
Internal error: Oops: 17 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 3 PID: 1468 Comm: kworker/u16:23 Not tainted 
5.6.0-rc1-next-20200211 #268
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: events_unbound async_run_entry_fn
PC is at xhci_suspend+0x12c/0x520
LR is at 0xa6aa9898
pc : [<c0724c90>]    lr : [<a6aa9898>]    psr: 60000093
sp : ec401df8  ip : 0000001a  fp : c12e7864
r10: 00000000  r9 : ecfb87b0  r8 : ecfb8220
r7 : 00000000  r6 : 00000000  r5 : 00000004  r4 : ecfb81f0
r3 : 00007d00  r2 : 00000001  r1 : 00000001  r0 : 00000000
Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c5387d  Table: 6bd4006a  DAC: 00000051
Process kworker/u16:23 (pid: 1468, stack limit = 0x6e4b6fba)
Stack: (0xec401df8 to 0xec402000)
...
[<c0724c90>] (xhci_suspend) from [<c061b4f4>] (dpm_run_callback+0xb4/0x3fc)
[<c061b4f4>] (dpm_run_callback) from [<c061bd5c>] 
(__device_suspend+0x134/0x7e8)
[<c061bd5c>] (__device_suspend) from [<c061c42c>] (async_suspend+0x1c/0x94)
[<c061c42c>] (async_suspend) from [<c0154bd0>] 
(async_run_entry_fn+0x48/0x1b8)
[<c0154bd0>] (async_run_entry_fn) from [<c0149b38>] 
(process_one_work+0x230/0x7bc)
[<c0149b38>] (process_one_work) from [<c014a108>] (worker_thread+0x44/0x524)
[<c014a108>] (worker_thread) from [<c01511fc>] (kthread+0x130/0x164)
[<c01511fc>] (kthread) from [<c01010b4>] (ret_from_fork+0x14/0x20)
Exception stack(0xec401fb0 to 0xec401ff8)
...
---[ end trace c72caf6487666442 ]---
note: kworker/u16:23[1468] exited with preempt_count 1

Reverting it fixes the NULL pointer issue. I can provide more 
information or do some other tests. Just let me know what will help to 
fix it.

 > ...

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland