Currently, there's no guarantee that udc->driver
will be valid when using soft_connect sysfs
interface. In fact, we can very easily trigger
a NULL pointer dereference by trying to disconnect
when a gadget driver isn't loaded.
Fix this bug:
~# echo disconnect > soft_connect
[ 33.685743] Unable to handle kernel NULL pointer dereference at virtual address 00000014
[ 33.694221] pgd = ed0cc000
[ 33.697174] [00000014] *pgd=ae351831, *pte=00000000, *ppte=00000000
[ 33.703766] Internal error: Oops: 17 [#1] SMP ARM
[ 33.708697] Modules linked in: xhci_plat_hcd xhci_hcd snd_soc_davinci_mcasp snd_soc_tlv320aic3x snd_soc_edma snd_soc_omap snd_soc_evm snd_soc_core dwc3 snd_compress snd_pcm_dmaengine snd_pcm snd_timer snd lis3lv02d_i2c matrix_keypad lis3lv02d dwc3_omap input_polldev soundcore
[ 33.734372] CPU: 0 PID: 1457 Comm: bash Not tainted 3.17.0-09740-ga93416e-dirty #345
[ 33.742457] task: ee71ce00 ti: ee68a000 task.ti: ee68a000
[ 33.748116] PC is at usb_udc_softconn_store+0xa4/0xec
[ 33.753416] LR is at mark_held_locks+0x78/0x90
[ 33.758057] pc : [<c04df128>] lr : [<c00896a4>] psr: 20000013
[ 33.758057] sp : ee68bec8 ip : c0c00008 fp : ee68bee4
[ 33.770050] r10: ee6b394c r9 : ee68bf80 r8 : ee6062c0
[ 33.775508] r7 : 00000000 r6 : ee6062c0 r5 : 0000000b r4 : ee739408
[ 33.782346] r3 : 00000000 r2 : 00000000 r1 : ee71d390 r0 : ee664170
[ 33.789168] Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
[ 33.796636] Control: 10c5387d Table: ad0cc059 DAC: 00000015
[ 33.802638] Process bash (pid: 1457, stack limit = 0xee68a248)
[ 33.808740] Stack: (0xee68bec8 to 0xee68c000)
[ 33.813299] bec0: 0000000b c0411284 ee6062c0 00000000 ee68bef4 ee68bee8
[ 33.821862] bee0: c04112ac c04df090 ee68bf14 ee68bef8 c01c2868 c0411290 0000000b ee6b3940
[ 33.830419] bf00: 00000000 00000000 ee68bf4c ee68bf18 c01c1a24 c01c2818 00000000 00000000
[ 33.838990] bf20: ee61b940 ee2f47c0 0000000b 000ce408 ee68bf80 c000f304 ee68a000 00000000
[ 33.847544] bf40: ee68bf7c ee68bf50 c0152dd8 c01c1960 ee68bf7c c0170af8 ee68bf7c ee2f47c0
[ 33.856099] bf60: ee2f47c0 000ce408 0000000b c000f304 ee68bfa4 ee68bf80 c0153330 c0152d34
[ 33.864653] bf80: 00000000 00000000 0000000b 000ce408 b6e7fb50 00000004 00000000 ee68bfa8
[ 33.873204] bfa0: c000f080 c01532e8 0000000b 000ce408 00000001 000ce408 0000000b 00000000
[ 33.881763] bfc0: 0000000b 000ce408 b6e7fb50 00000004 0000000b 00000000 000c5758 00000000
[ 33.890319] bfe0: 00000000 bec2c924 b6de422d b6e1d226 40000030 00000001 75716d2f 00657565
[ 33.898890] [<c04df128>] (usb_udc_softconn_store) from [<c04112ac>] (dev_attr_store+0x28/0x34)
[ 33.907920] [<c04112ac>] (dev_attr_store) from [<c01c2868>] (sysfs_kf_write+0x5c/0x60)
[ 33.916200] [<c01c2868>] (sysfs_kf_write) from [<c01c1a24>] (kernfs_fop_write+0xd0/0x194)
[ 33.924773] [<c01c1a24>] (kernfs_fop_write) from [<c0152dd8>] (vfs_write+0xb0/0x1bc)
[ 33.932874] [<c0152dd8>] (vfs_write) from [<c0153330>] (SyS_write+0x54/0xb0)
[ 33.940247] [<c0153330>] (SyS_write) from [<c000f080>] (ret_fast_syscall+0x0/0x48)
[ 33.948160] Code: e1a01007 e12fff33 e5140004 e5143008 (e5933014)
[ 33.954625] ---[ end trace f849bead94eab7ea ]---
Fixes:
|
||
---|---|---|
.. | ||
atm | ||
c67x00 | ||
chipidea | ||
class | ||
common | ||
core | ||
dwc2 | ||
dwc3 | ||
early | ||
gadget | ||
host | ||
image | ||
misc | ||
mon | ||
musb | ||
phy | ||
renesas_usbhs | ||
serial | ||
storage | ||
usbip | ||
wusbcore | ||
Kconfig | ||
Makefile | ||
README | ||
usb-skeleton.c |
To understand all the Linux-USB framework, you'll use these resources: * This source code. This is necessarily an evolving work, and includes kerneldoc that should help you get a current overview. ("make pdfdocs", and then look at "usb.pdf" for host side and "gadget.pdf" for peripheral side.) Also, Documentation/usb has more information. * The USB 2.0 specification (from www.usb.org), with supplements such as those for USB OTG and the various device classes. The USB specification has a good overview chapter, and USB peripherals conform to the widely known "Chapter 9". * Chip specifications for USB controllers. Examples include host controllers (on PCs, servers, and more); peripheral controllers (in devices with Linux firmware, like printers or cell phones); and hard-wired peripherals like Ethernet adapters. * Specifications for other protocols implemented by USB peripheral functions. Some are vendor-specific; others are vendor-neutral but just standardized outside of the www.usb.org team. Here is a list of what each subdirectory here is, and what is contained in them. core/ - This is for the core USB host code, including the usbfs files and the hub class driver ("hub_wq"). host/ - This is for USB host controller drivers. This includes UHCI, OHCI, EHCI, and others that might be used with more specialized "embedded" systems. gadget/ - This is for USB peripheral controller drivers and the various gadget drivers which talk to them. Individual USB driver directories. A new driver should be added to the first subdirectory in the list below that it fits into. image/ - This is for still image drivers, like scanners or digital cameras. ../input/ - This is for any driver that uses the input subsystem, like keyboard, mice, touchscreens, tablets, etc. ../media/ - This is for multimedia drivers, like video cameras, radios, and any other drivers that talk to the v4l subsystem. ../net/ - This is for network drivers. serial/ - This is for USB to serial drivers. storage/ - This is for USB mass-storage drivers. class/ - This is for all USB device drivers that do not fit into any of the above categories, and work for a range of USB Class specified devices. misc/ - This is for all USB device drivers that do not fit into any of the above categories.