• Peter Hurley's avatar
    tty: Fix GPF in flush_to_ldisc() · 9ce119f3
    Peter Hurley authored
    A line discipline which does not define a receive_buf() method can
    can cause a GPF if data is ever received [1]. Oddly, this was known
    to the author of n_tracesink in 2011, but never fixed.
    
    [1] GPF report
        BUG: unable to handle kernel NULL pointer dereference at           (null)
        IP: [<          (null)>]           (null)
        PGD 3752d067 PUD 37a7b067 PMD 0
        Oops: 0010 [#1] SMP KASAN
        Modules linked in:
        CPU: 2 PID: 148 Comm: kworker/u10:2 Not tainted 4.4.0-rc2+ #51
        Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
        Workqueue: events_unbound flush_to_ldisc
        task: ffff88006da94440 ti: ffff88006db60000 task.ti: ffff88006db60000
        RIP: 0010:[<0000000000000000>]  [<          (null)>]           (null)
        RSP: 0018:ffff88006db67b50  EFLAGS: 00010246
        RAX: 0000000000000102 RBX: ffff88003ab32f88 RCX: 0000000000000102
        RDX: 0000000000000000 RSI: ffff88003ab330a6 RDI: ffff88003aabd388
        RBP: ffff88006db67c48 R08: ffff88003ab32f9c R09: ffff88003ab31fb0
        R10: ffff88003ab32fa8 R11: 0000000000000000 R12: dffffc0000000000
        R13: ffff88006db67c20 R14: ffffffff863df820 R15: ffff88003ab31fb8
        FS:  0000000000000000(0000) GS:ffff88006dc00000(0000) knlGS:0000000000000000
        CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
        CR2: 0000000000000000 CR3: 0000000037938000 CR4: 00000000000006e0
        Stack:
         ffffffff829f46f1 ffff88006da94bf8 ffff88006da94bf8 0000000000000000
         ffff88003ab31fb0 ffff88003aabd438 ffff88003ab31ff8 ffff88006430fd90
         ffff88003ab32f9c ffffed0007557a87 1ffff1000db6cf78 ffff88003ab32078
        Call Trace:
         [<ffffffff8127cf91>] process_one_work+0x8f1/0x17a0 kernel/workqueue.c:2030
         [<ffffffff8127df14>] worker_thread+0xd4/0x1180 kernel/workqueue.c:2162
         [<ffffffff8128faaf>] kthread+0x1cf/0x270 drivers/block/aoe/aoecmd.c:1302
         [<ffffffff852a7c2f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:468
        Code:  Bad RIP value.
        RIP  [<          (null)>]           (null)
         RSP <ffff88006db67b50>
        CR2: 0000000000000000
        ---[ end trace a587f8947e54d6ea ]---
    Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    9ce119f3
tty_buffer.c 15.6 KB