net: macb: linux-next: null pointer dereference in phylink_major_config()

[Nicolas.Ferre]

Hi,

Heads-up on this kernel Oops that happened and has been observed on
linux-next since 20201103 and was not existing in 20201030.

I didn't went further until now but wanted to report it
as soon as possible.
Could it be related to newly included patch
e4e143e26ce8 ("net: macb: add support for high speed interface")?

Tell us if you saw it on other platforms or if you couldn't reproduce it.

[..]
Linux version 5.10.0-rc2-next-20201104 (root@linux-ci-43h78-cjbps) (arm-linux-gnueabihf-gcc (GNU Toolchain for the A-profile Architecture 8.3-2019.03 (arm-rel-8.36)) 8.3.0, GNU ld (GNU Toolchain for the A-profile Architecture 8.3-2019.03 (arm-rel-8.36)) 2.32.0.20190321) #2 Wed Nov 4 07:31:39 UTC 2020

[..]
OF: fdt: Machine model: Atmel SAMA5D4 Xplained

[..]
libphy: Fixed MDIO Bus: probed
libphy: MACB_mii_bus: probed
macb f8020000.ethernet eth0: Cadence GEM rev 0x00020120 at 0xf8020000 irq 27 (fc:c2:3d:0d:eb:27)

[..]

Configuring network interfaces...
macb f8020000.ethernet eth0: PHY [f8020000.ethernet-ffffffff:01] driver [Micrel KSZ8081 or KSZ8091] (irq=46)
macb f8020000.ethernet eth0: configuring for phy/rmii link mode
8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = 8fd7a220
[00000000] *pgd=00000000
Internal error: Oops: 80000005 [#1] ARM
Modules linked in:
CPU: 0 PID: 250 Comm: ip Not tainted 5.10.0-rc2-next-20201104 #2
Hardware name: Atmel SAMA5
PC is at 0x0
LR is at phylink_major_config+0x84/0x1a8
pc : [<00000000>]    lr : [<c0509ebc>]    psr: a0050013
sp : c1cdb8f0  ip : c09530c4  fp : c09530d4
r10: c12204e0  r9 : 00000000  r8 : 00000001
r7 : 00000001  r6 : 00000000  r5 : c1cdb918  r4 : c1266800
r3 : c1cdb918  r2 : 00000007  r1 : 00000000  r0 : c1221100
Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c53c7d  Table: 21d60059  DAC: 00000051
Process ip (pid: 250, stack limit = 0x362b1cfa)
Stack: (0xc1cdb8f0 to 0xc1cdc000)
b8e0:                                     00000001 c0a58564 c1cdb8f0 c1266800
b900: c0d03208 c1cdb918 c1220000 c050b3c8 c0a4bc38 00000000 00000000 00000000
b920: 00000000 00000000 00000000 00000000 00000007 ffffffff 000000ff 00000000
b940: 00000000 a0250c4f c12204e0 00000000 dfbf0318 c051c450 c12206a4 c1220000
b960: c1221000 c1220668 00000001 c051fbac 00000000 fffffff1 c1220000 c0d03208
b980: c09530d4 c1cdbd48 00001002 c1cdbd48 c1cdbd48 c064af9c 00000000 00000000
b9a0: 00000000 c1220000 c1cdbd48 a0250c4f 00000000 c1220000 00000001 00001003
b9c0: c0d03208 c064b368 00000000 00000000 00000000 00000000 00000000 a0250c4f
b9e0: 00000000 c1220000 00001002 00000000 c1220138 c1cdbc68 c1082810 c064b3e0
ba00: c0d03208 c1cdbb88 c1220000 c1d29900 c1cdbc68 c0656f20 00000000 00000000
ba20: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ba40: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ba60: 00000000 a0250c4f 00000000 c1082820 c1d29900 c1082800 c1cdbd48 a0250c4f
ba80: c1cdbd48 c1082800 c1220000 00000000 c1cdbd48 00000000 00000000 00000000
baa0: c097c1dc c065d2c4 c1cdbb88 c1cdbc68 00000000 c1220000 c0d3cce0 c1082810
bac0: 00000000 c0d03208 c1d44a00 c1d29900 00000009 c070df20 c1d29900 00000000
bae0: 00000000 00000000 00000000 00000000 00000000 00000000 c1bd0000 c0d3d72c
bb00: 00000180 c03a6a70 c1d29900 c1bd03c0 c1d29900 c03a6ab4 c1d29900 c065c0d0
bb20: 00000003 a0250c4f c0656170 c1cdbb54 c0d03208 c068a824 f601f5ae c101e000
bb40: c1cdbb38 00040000 02940000 00000000 00010000 00000000 c068a2c8 c0688238
bb60: c1cc7c00 c0d03208 a0250c4f c1cc7c00 c1d29900 000003bc c1087400 c1087564
bb80: f601f5ae c0d03208 00000000 00000000 00000000 00000000 00000000 00000000
bba0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bbc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bbe0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bc00: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bc20: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bc40: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bc60: 00000000 00000000 c1082800 00000000 00000000 00000000 00000000 00000000
bc80: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bca0: 00000000 00000000 c0d03208 c064ce3c 00000000 a0250c4f 00000000 c1d44a00
bcc0: c1d29900 c1082800 c1cdbd48 c1d29900 c1cdbd48 c1082800 c0d5fb34 c065d548
bce0: 00000000 00000000 c0d03208 c0d5fb34 c1d29900 c0657e90 c1d09ac0 c10800c0
bd00: c0d03208 c1cdbf60 000003bc c0d03208 c1d41bbc c1cdbd3c c0d03208 a0250c4f
bd20: 00000000 c1d29900 c0d03208 c0657c48 c1082800 00000020 00000000 c0d03208
bd40: 00000000 c068cb10 00000000 00000000 00000000 00000000 00000000 00000000
bd60: 00000000 00000000 00000000 a0250c4f c1087400 00000020 c1d29900 c1cc7400
bd80: c1cc7564 c068c270 7fffffff a0250c4f 00000008 c1cdbf58 c0d03208 c1cc7400
bda0: c1d29900 00000020 00000000 c068c4d8 00000001 c035ca40 00000000 c1cdbe64
bdc0: 00000000 c1cdbe64 c1024780 00000000 000000fa 00000000 00000000 a0250c4f
bde0: 00000000 c1cdbf58 c068c318 00000000 c0d03208 c15b9a80 c1cdbe0c 00000000
be00: 00000020 c0628408 00000000 00000000 c0d03208 c0629af8 c1cdbe60 c1cdbf60
be20: 00000000 c101e000 bea7176c a0250c4f 00000000 c0d03208 c1cdbf58 00000000
be40: c15b9a80 00000000 00000000 00000128 00546cc0 c0629b84 00000000 02940000
be60: 00000000 bea7179c 00000020 c068a2c8 c0688238 00040000 02940000 00000000
be80: 00010000 00000000 c068a2c8 a0250c4f 00000007 ffffffff c15b9c70 c097b500
bea0: c0d03208 00000010 00000000 00000000 5ac3c35a a0050013 00000000 c1cdbebc
bec0: c1cdbebc a0250c4f fffffe30 c1c76300 002e0003 c15b9c70 c15e4110 c101b490
bee0: fffffe30 c0d03208 5ac3c35a c01cdc68 00000000 c15b9c70 00000000 00000000
bf00: c1d0aaa8 00000000 c1c804c4 c1c80180 00000000 c1c804c4 5ac3c35a c012ed04
bf20: ffffe000 a0250c4f c0100264 c0d03208 bea71718 00000000 c15b9a80 c0100264
bf40: c1cda000 c0629f7c 00000000 00000000 00000000 fffffff7 c1cdbea4 0000000c
bf60: 00000005 00000000 00000000 c1cdbe6c 00000000 c1cdbfb0 00000000 c1c76301
bf80: 00000000 00000000 00000000 a0250c4f b6f644d0 00000000 00000010 b6f644d0
bfa0: 00000128 c0100060 00000000 00000010 00000003 bea71718 00000000 00000000
bfc0: 00000000 00000010 b6f644d0 00000128 00547008 5aa2f689 00000000 00546cc0
bfe0: 00000128 bea716b8 b6e8cd7f b6e0eba6 60050030 00000003 00000000 00000000
[<c0509ebc>] (phylink_major_config) from [<c050b3c8>] (phylink_start+0x190/0x33c)
[<c050b3c8>] (phylink_start) from [<c051c450>] (macb_phylink_connect+0x40/0xb4)
[<c051c450>] (macb_phylink_connect) from [<c051fbac>] (macb_open+0x1e0/0x2a0)
[<c051fbac>] (macb_open) from [<c064af9c>] (__dev_open+0xfc/0x180)
[<c064af9c>] (__dev_open) from [<c064b368>] (__dev_change_flags+0x16c/0x1cc)
[<c064b368>] (__dev_change_flags) from [<c064b3e0>] (dev_change_flags+0x18/0x48)
[<c064b3e0>] (dev_change_flags) from [<c0656f20>] (do_setlink+0x2d8/0xbdc)
[<c0656f20>] (do_setlink) from [<c065d2c4>] (__rtnl_newlink+0x4e8/0x72c)
[<c065d2c4>] (__rtnl_newlink) from [<c065d548>] (rtnl_newlink+0x40/0x5c)
[<c065d548>] (rtnl_newlink) from [<c0657e90>] (rtnetlink_rcv_msg+0x248/0x2c0)
[<c0657e90>] (rtnetlink_rcv_msg) from [<c068cb10>] (netlink_rcv_skb+0xb8/0x110)
[<c068cb10>] (netlink_rcv_skb) from [<c068c270>] (netlink_unicast+0x188/0x230)
[<c068c270>] (netlink_unicast) from [<c068c4d8>] (netlink_sendmsg+0x1c0/0x408)
[<c068c4d8>] (netlink_sendmsg) from [<c0628408>] (____sys_sendmsg+0x1a4/0x238)
[<c0628408>] (____sys_sendmsg) from [<c0629b84>] (___sys_sendmsg+0x6c/0x98)
[<c0629b84>] (___sys_sendmsg) from [<c0629f7c>] (__sys_sendmsg+0x50/0x8c)
[<c0629f7c>] (__sys_sendmsg) from [<c0100060>] (ret_fast_syscall+0x0/0x58)
Exception stack(0xc1cdbfa8 to 0xc1cdbff0)
bfa0:                   00000000 00000010 00000003 bea71718 00000000 00000000
bfc0: 00000000 00000010 b6f644d0 00000128 00547008 5aa2f689 00000000 00546cc0
bfe0: 00000128 bea716b8 b6e8cd7f b6e0eba6
Code: bad PC value
---[ end trace f10e0fdf87618077 ]---

Best regards,
-- 
Nicolas Ferre