[ Upstream commit 24d413a ] Fix a race which leads to an Oops with NULL pointer dereference. The dereference is in brcmf_config_dongle() when cfg_to_ndev() attempts to get net_device structure of interface with index 0 via if2bss mapping. This shouldn't fail because of check for bus being ready in brcmf_netdev_open(), but it's not synchronised with USB disconnect and there is a race: after the check the bus can be marked down and the mapping for interface 0 may be gone. Solve this by modifying disconnect handling so that the removal of mapping of ifidx to brcmf_if structure happens after netdev removal (which is synchronous with brcmf_netdev_open() thanks to rtln being locked in devinet_ioctl()). This assures brcmf_netdev_open() returns before the mapping is removed during disconnect. Unable to handle kernel NULL pointer dereference at virtual address 00000008 pgd = bcae2612 [00000008] *pgd=8be73831 Internal error: Oops: 17 [#1] PREEMPT SMP ARM Modules linked in: brcmfmac brcmutil nf_log_ipv4 nf_log_common xt_LOG xt_limit iptable_mangle xt_connmark xt_tcpudp xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter ip_tables x_tables usb_f_mass_storage usb_f_rndis u_ether usb_serial_simple usbserial cdc_acm smsc95xx usbnet ci_hdrc_imx ci_hdrc usbmisc_imx ulpi 8250_exar 8250_pci 8250 8250_base libcomposite configfs udc_core [last unloaded: brcmutil] CPU: 2 PID: 24478 Comm: ifconfig Not tainted 4.19.23-00078-ga62866d-dirty #115 Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) PC is at brcmf_cfg80211_up+0x94/0x29c [brcmfmac] LR is at brcmf_cfg80211_up+0x8c/0x29c [brcmfmac] pc : [<7f26a91c>] lr : [<7f26a914>] psr: a0070013 sp : eca99d28 ip : 00000000 fp : ee9c6c00 r10: 00000036 r9 : 00000000 r8 : ece4002c r7 : edb5b800 r6 : 00000000 r5 : 80f08448 r4 : edb5b968 r3 : ffffffff r2 : 00000000 r1 : 00000002 r0 : 00000000 Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 10c5387d Table: 7ca0c04a DAC: 00000051 Process ifconfig (pid: 24478, stack limit = 0xd9e85a0e) Stack: (0xeca99d28 to 0xeca9a000) 9d20: 00000000 80f873b0 0000000d 80f08448 eca99d68 50d45f32 9d40: 7f27de94 ece40000 80f08448 80f08448 7f27de94 ece4002c 00000000 00000036 9d60: ee9c6c00 7f27262c 00001002 50d45f32 ece40000 00000000 80f08448 80772008 9d80: 00000001 00001043 00001002 ece40000 00000000 50d45f32 ece40000 00000001 9da0: 80f08448 00001043 00001002 807723d0 00000000 50d45f32 80f08448 eca99e5 9dc0: 80f87113 50d45f32 80f08448 ece40000 ece40138 00001002 80f08448 00000000 9de0: 00000000 80772434 edbd5380 eca99e5 edbd5380 80f08448 ee9c6c0c 80805f7 9e00: 00000000 ede08e00 00008914 ece40000 00000014 ee9c6c0c 600c001 00001043 9e20: 0208a8c0 ffffffff 00000000 50d45f32 eca98000 80f08448 7ee9fc38 00008914 9e40: 80f68e40 00000051 eca98000 00000036 00000003 80808b9c 6e616c77 00000030 9e60: 00000000 00000000 00001043 0208a8c0 ffffffff 00000000 80f08448 00000000 9e80: 00000000 816d8b20 600c001 00000001 ede09320 801763d4 00000000 50d45f32 9ea0: eca98000 80f08448 7ee9fc38 50d45f32 00008914 80f08448 7ee9fc38 80f68e40 9ec0: ed531540 8074721c 00000800 00000001 00000000 6e616c77 00000030 00000000 9ee0: 00000000 00001002 0208a8c0 ffffffff 00000000 50d45f32 80f08448 7ee9fc38 9f00: ed531560 ec8fc900 80285a6c 80285138 edb910c0 00000000 ecd91008 ede08e00 9f20: 80f08448 00000000 00000000 816d8b20 600c001 00000001 ede09320 801763d4 9f40: 00000000 50d45f32 00021000 edb91118 edb910c0 80f08448 01b29000 edb91118 9f60: eca99f7c 50d45f32 00021000 ec8fc900 00000003 ec8fc900 00008914 7ee9fc38 9f80: eca98000 00000036 00000003 80285a6c 00086364 7ee9fe1c 000000c3 00000036 9fa0: 801011c4 80101000 00086364 7ee9fe1c 00000003 00008914 7ee9fc38 00086364 9fc0: 00086364 7ee9fe1c 000000c3 00000036 0008630c 7ee9fe1c 7ee9fc38 00000003 9fe0: 000a42b8 7ee9fbd4 00019914 76e09acc 600c0010 00000003 00000000 00000000 [<7f26a91c>] (brcmf_cfg80211_up [brcmfmac]) from [<7f27262c>] (brcmf_netdev_open+0x74/0xe8 [brcmfmac]) [<7f27262c>] (brcmf_netdev_open [brcmfmac]) from [<80772008>] (__dev_open+0xcc/0x150) [<80772008>] (__dev_open) from [<807723d0>] (__dev_change_flags+0x168/0x1b4) [<807723d0>] (__dev_change_flags) from [<80772434>] (dev_change_flags+0x18/0x48) [<80772434>] (dev_change_flags) from [<80805f70>] (devinet_ioctl+0x67c/0x79c) [<80805f70>] (devinet_ioctl) from [<80808b9c>] (inet_ioctl+0x210/0x3d4) [<80808b9c>] (inet_ioctl) from [<8074721c>] (sock_ioctl+0x350/0x524) [<8074721c>] (sock_ioctl) from [<80285138>] (do_vfs_ioctl+0xb0/0x9b0) [<80285138>] (do_vfs_ioctl) from [<80285a6c>] (ksys_ioctl+0x34/0x5c) [<80285a6c>] (ksys_ioctl) from [<80101000>] (ret_fast_syscall+0x0/0x28) Exception stack(0xeca99fa8 to 0xeca99ff0) 9fa0: 00086364 7ee9fe1c 00000003 00008914 7ee9fc38 00086364 9fc0: 00086364 7ee9fe1c 000000c3 00000036 0008630c 7ee9fe1c 7ee9fc38 00000003 9fe0: 000a42b8 7ee9fbd4 00019914 76e09acc Code: e5970328 eb002021 e1a02006 e3a01002 (e5909008) ---[ end trace 5cbac2333f3ac5df ]--- Signed-off-by: Piotr Figiel <p.figiel@camlintechnologies.com> Signed-off-by: Kalle Valo <kvalo@codeaurora.org> Signed-off-by: Sasha Levin <sashal@kernel.org>

Aufs in xu4 4.0 kernel branch #115

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