• Rob Herring's avatar
    tty: serial_core: fix NULL struct tty pointer access in uart_write_wakeup · d0f4bce2
    Rob Herring authored
    Since commit 761ed4a9 ("tty: serial_core: convert uart_close to
    use tty_port_close"), the serial console is broken on various systems
    and typing "reboot" splats the following on the serial console:
    
    INIT: Sending p[  427.863916] BUG: unable to handle kernel NULL pointer dereference at 00000000000001e0
    [  427.885156] IP: [] tty_wakeup+0xc/0x70
    [  427.898337] PGD 0 [  427.902051]
    [  427.907498] Oops: 0000 [#1] PREEMPT SMP
    [  427.917635] Modules linked in: nfsv3 nfs_acl nfs fscache lockd
    sunrpc grace edd af_packet cpufreq_conservative cpufreq_userspace
    cpufreq_powersave fuse loop md_mod dm_mod joydev hid_generic usbhid
    ipmi_ssif ohci_pci ohci_hcd ehci_pci ehci_hcd e1000e ptp firewire_ohci
    edac_core pps_core tpm_infineon sp5100_tco firewire_core acpi_cpufreq
    serio_raw pcspkr fjes usbcore shpchp edac_mce_amd tpm_tis ipmi_si
    tpm_tis_core i2c_piix4 k10temp sg ipmi_msghandler tpm sr_mod button
    cdrom kvm_amd kvm irqbypass crc_itu_t ast ttm drm_kms_helper drm
    fb_sys_fops sysimgblt sysfillrect syscopyarea i2c_algo_bit scsi_dh_rdac
    scsi_dh_alua scsi_dh_emc scsi_dh_hp_sw ata_generic pata_atiixp
    [  428.054179] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.0-rc1-1.g73e3f23-default #1
    [  428.072868] Hardware name: System manufacturer System Product Name/KGP(M)E-D16, BIOS 0902    12/03/2010
    [  428.094755] task: ffffffffa2c0d500 task.stack: ffffffffa2c00000
    [  428.109717] RIP: 0010:[]  [] tty_wakeup+0xc/0x70
    [  428.128407] RSP: 0018:ffff9a1a5fc03df8  EFLAGS: 00010086
    [  428.142184] RAX: ffff9a1857258000 RBX: ffffffffa3050ea0 RCX: 0000000000000000
    [  428.159649] RDX: 000000000000001b RSI: 0000000000000000 RDI: 0000000000000000
    [  428.177109] RBP: ffff9a1a5fc03e08 R08: 0000000000000000 R09: 0000000000000000
    [  428.194547] R10: 0000000000021c77 R11: 0000000000000000 R12: ffff9a1857258000
    [  428.212002] R13: 0000000000000000 R14: 0000000000000020 R15: 0000000000000020
    [  428.229481] FS:  0000000000000000(0000) GS:ffff9a1a5fc00000(0000) knlGS:0000000000000000
    [  428.248938] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  428.263726] CR2: 00000000000001e0 CR3: 0000000390c06000 CR4: 00000000000006f0
    [  428.281331] Stack:
    [  428.288696]  ffffffffa3050ea0 ffff9a1857258000 ffff9a1a5fc03e18 ffffffffa24e0ab1
    [  428.307064]  ffff9a1a5fc03e40 ffffffffa24e8865 ffffffffa3050ea0 00000000000000c2
    [  428.325456]  0000000000000046 ffff9a1a5fc03e78 ffffffffa24e8a5f ffffffffa3050ea0
    [  428.343905] Call Trace:
    [  428.352319]   [  428.356216]  [] uart_write_wakeup+0x21/0x30
    
    The problem is for console ports, the serial port is not shutdown and
    interrupts may fire after the struct tty is gone. Simply calling the
    tty_port helper tty_port_tty_wakeup instead of tty_wakeup directly will
    ensure there is a valid struct tty.
    
    Fixes: 761ed4a9 ("tty: serial_core: convert uart_close to use tty_port_close")
    Reported-by: default avatarBorislav Petkov <bp@alien8.de>
    Reported-by: default avatarMike Galbraith <mgalbraith@suse.de>
    Cc: Jiri Slaby <jslaby@suse.cz>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: linux-serial@vger.kernel.org
    Signed-off-by: default avatarRob Herring <robh@kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    d0f4bce2
serial_core.c 73.8 KB