ab4e6ee578
Since a phy_device is added to the global mdio_bus list during phy_device_register(), but a phy_device's phy_driver doesn't get attached until phy_probe(). It's possible of_phy_find_device() in xgmiitorgmii will return a valid phy with a NULL phy_driver. Leading to a NULL pointer access during the memcpy(). Fixes this Oops: Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = c0004000 [00000000] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.14.40 #1 Hardware name: Xilinx Zynq Platform task: ce4c8d00 task.stack: ce4ca000 PC is at memcpy+0x48/0x330 LR is at xgmiitorgmii_probe+0x90/0xe8 pc : [<c074bc68>] lr : [<c0529548>] psr: 20000013 sp : ce4cbb54 ip : 00000000 fp : ce4cbb8c r10: 00000000 r9 : 00000000 r8 : c0c49178 r7 : 00000000 r6 : cdc14718 r5 : ce762800 r4 : cdc14710 r3 : 00000000 r2 : 00000054 r1 : 00000000 r0 : cdc14718 Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 18c5387d Table: 0000404a DAC: 00000051 Process swapper/0 (pid: 1, stack limit = 0xce4ca210) ... [<c074bc68>] (memcpy) from [<c0529548>] (xgmiitorgmii_probe+0x90/0xe8) [<c0529548>] (xgmiitorgmii_probe) from [<c0526a94>] (mdio_probe+0x28/0x34) [<c0526a94>] (mdio_probe) from [<c04db98c>] (driver_probe_device+0x254/0x414) [<c04db98c>] (driver_probe_device) from [<c04dbd58>] (__device_attach_driver+0xac/0x10c) [<c04dbd58>] (__device_attach_driver) from [<c04d96f4>] (bus_for_each_drv+0x84/0xc8) [<c04d96f4>] (bus_for_each_drv) from [<c04db5bc>] (__device_attach+0xd0/0x134) [<c04db5bc>] (__device_attach) from [<c04dbdd4>] (device_initial_probe+0x1c/0x20) [<c04dbdd4>] (device_initial_probe) from [<c04da8fc>] (bus_probe_device+0x98/0xa0) [<c04da8fc>] (bus_probe_device) from [<c04d8660>] (device_add+0x43c/0x5d0) [<c04d8660>] (device_add) from [<c0526cb8>] (mdio_device_register+0x34/0x80) [<c0526cb8>] (mdio_device_register) from [<c0580b48>] (of_mdiobus_register+0x170/0x30c) [<c0580b48>] (of_mdiobus_register) from [<c05349c4>] (macb_probe+0x710/0xc00) [<c05349c4>] (macb_probe) from [<c04dd700>] (platform_drv_probe+0x44/0x80) [<c04dd700>] (platform_drv_probe) from [<c04db98c>] (driver_probe_device+0x254/0x414) [<c04db98c>] (driver_probe_device) from [<c04dbc58>] (__driver_attach+0x10c/0x118) [<c04dbc58>] (__driver_attach) from [<c04d9600>] (bus_for_each_dev+0x8c/0xd0) [<c04d9600>] (bus_for_each_dev) from [<c04db1fc>] (driver_attach+0x2c/0x30) [<c04db1fc>] (driver_attach) from [<c04daa98>] (bus_add_driver+0x50/0x260) [<c04daa98>] (bus_add_driver) from [<c04dc440>] (driver_register+0x88/0x108) [<c04dc440>] (driver_register) from [<c04dd6b4>] (__platform_driver_register+0x50/0x58) [<c04dd6b4>] (__platform_driver_register) from [<c0b31248>] (macb_driver_init+0x24/0x28) [<c0b31248>] (macb_driver_init) from [<c010203c>] (do_one_initcall+0x60/0x1a4) [<c010203c>] (do_one_initcall) from [<c0b00f78>] (kernel_init_freeable+0x15c/0x1f8) [<c0b00f78>] (kernel_init_freeable) from [<c0763d10>] (kernel_init+0x18/0x124) [<c0763d10>] (kernel_init) from [<c0112d74>] (ret_from_fork+0x14/0x20) Code: ba000002 f5d1f03c f5d1f05c f5d1f07c (e8b151f8) ---[ end trace 3e4ec21905820a1f ]--- Signed-off-by: Brandon Maier <brandon.maier@rockwellcollins.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.