Piotr Figiel <p.figiel@xxxxxxxxxxxxxxxxxxxxxx> wrote: > 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 eca99e58 > 9dc0: 80f87113 50d45f32 80f08448 ece40000 ece40138 00001002 80f08448 00000000 > 9de0: 00000000 80772434 edbd5380 eca99e58 edbd5380 80f08448 ee9c6c0c 80805f70 > 9e00: 00000000 ede08e00 00008914 ece40000 00000014 ee9c6c0c 600c0013 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 600c0013 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 600c0013 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@xxxxxxxxxxxxxxxxxxxxxx> Patch applied to wireless-drivers-next.git, thanks. 24d413a31afa brcmfmac: fix Oops when bringing up interface during USB disconnect -- https://patchwork.kernel.org/patch/10850845/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
