1. 25 Apr, 2019 2 commits
    • Jiri Slaby's avatar
      TTY: serial_core, add ->install · 4cdd17ba
      Jiri Slaby authored
      We need to compute the uart state only on the first open. This is
      usually what is done in the ->install hook. serial_core used to do this
      in ->open on every open. So move it to ->install.
      
      As a side effect, it ensures the state is set properly in the window
      after tty_init_dev is called, but before uart_open. This fixes a bunch
      of races between tty_open and flush_to_ldisc we were dealing with
      recently.
      
      One of such bugs was attempted to fix in commit fedb5760 (serial:
      fix race between flush_to_ldisc and tty_open), but it only took care of
      a couple of functions (uart_start and uart_unthrottle).  I was able to
      reproduce the crash on a SLE system, but in uart_write_room which is
      also called from flush_to_ldisc via process_echoes. I was *unable* to
      reproduce the bug locally. It is due to having this patch in my queue
      since 2012!
      
       general protection fault: 0000 [#1] SMP KASAN PTI
       CPU: 1 PID: 5 Comm: kworker/u4:0 Tainted: G             L 4.12.14-396-default #1 SLE15-SP1 (unreleased)
       Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c89-prebuilt.qemu.org 04/01/2014
       Workqueue: events_unbound flush_to_ldisc
       task: ffff8800427d8040 task.stack: ffff8800427f0000
       RIP: 0010:uart_write_room+0xc4/0x590
       RSP: 0018:ffff8800427f7088 EFLAGS: 00010202
       RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
       RDX: 000000000000002f RSI: 00000000000000ee RDI: ffff88003888bd90
       RBP: ffffffffb9545850 R08: 0000000000000001 R09: 0000000000000400
       R10: ffff8800427d825c R11: 000000000000006e R12: 1ffff100084fee12
       R13: ffffc900004c5000 R14: ffff88003888bb28 R15: 0000000000000178
       FS:  0000000000000000(0000) GS:ffff880043300000(0000) knlGS:0000000000000000
       CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
       CR2: 0000561da0794148 CR3: 000000000ebf4000 CR4: 00000000000006e0
       Call Trace:
        tty_write_room+0x6d/0xc0
        __process_echoes+0x55/0x870
        n_tty_receive_buf_common+0x105e/0x26d0
        tty_ldisc_receive_buf+0xb7/0x1c0
        tty_port_default_receive_buf+0x107/0x180
        flush_to_ldisc+0x35d/0x5c0
      ...
      
      0 in rbx means tty->driver_data is NULL in uart_write_room. 0x178 is
      tried to be dereferenced (0x178 >> 3 is 0x2f in rdx) at
      uart_write_room+0xc4. 0x178 is exactly (struct uart_state *)NULL->refcount
      used in uart_port_lock from uart_write_room.
      
      So revert the upstream commit here as my local patch should fix the
      whole family.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Cc: Li RongQing <lirongqing@baidu.com>
      Cc: Wang Li <wangli39@baidu.com>
      Cc: Zhang Yu <zhangyu31@baidu.com>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: stable <stable@vger.kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      4cdd17ba
    • Sugaya Taichi's avatar
      serial: Fix using plain integer instead of Null pointer · 6bc3703d
      Sugaya Taichi authored
      Fix build warning that using plain integer as Null pointer.
      This is reported by kbuild test robot.
      
      Fixes: ba44dc04 ("serial: Add Milbeaut serial control")
      Signed-off-by: default avatarSugaya Taichi <sugaya.taichi@socionext.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      6bc3703d
  2. 21 Apr, 2019 2 commits
  3. 20 Apr, 2019 11 commits
  4. 19 Apr, 2019 25 commits