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    Subject[PATCH 4.19 198/276] brcmfmac: fix Oops when bringing up interface during USB disconnect
    Date
    [ Upstream commit 24d413a31afaee9bbbf79226052c386b01780ce2 ]

    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@camlintechnologies.com>
    Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    .../net/wireless/broadcom/brcm80211/brcmfmac/core.c | 10 +++++++---
    1 file changed, 7 insertions(+), 3 deletions(-)

    diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
    index 09c5f67f4089e..36a04c1144e5d 100644
    --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
    +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
    @@ -784,17 +784,17 @@ static void brcmf_del_if(struct brcmf_pub *drvr, s32 bsscfgidx,
    bool rtnl_locked)
    {
    struct brcmf_if *ifp;
    + int ifidx;

    ifp = drvr->iflist[bsscfgidx];
    - drvr->iflist[bsscfgidx] = NULL;
    if (!ifp) {
    brcmf_err("Null interface, bsscfgidx=%d\n", bsscfgidx);
    return;
    }
    brcmf_dbg(TRACE, "Enter, bsscfgidx=%d, ifidx=%d\n", bsscfgidx,
    ifp->ifidx);
    - if (drvr->if2bss[ifp->ifidx] == bsscfgidx)
    - drvr->if2bss[ifp->ifidx] = BRCMF_BSSIDX_INVALID;
    + ifidx = ifp->ifidx;
    +
    if (ifp->ndev) {
    if (bsscfgidx == 0) {
    if (ifp->ndev->netdev_ops == &brcmf_netdev_ops_pri) {
    @@ -822,6 +822,10 @@ static void brcmf_del_if(struct brcmf_pub *drvr, s32 bsscfgidx,
    brcmf_p2p_ifp_removed(ifp, rtnl_locked);
    kfree(ifp);
    }
    +
    + drvr->iflist[bsscfgidx] = NULL;
    + if (drvr->if2bss[ifidx] == bsscfgidx)
    + drvr->if2bss[ifidx] = BRCMF_BSSIDX_INVALID;
    }

    void brcmf_remove_interface(struct brcmf_if *ifp, bool rtnl_locked)
    --
    2.20.1


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