1. 03 Feb, 2016 1 commit
    • Takashi Iwai's avatar
      ALSA: rawmidi: Make snd_rawmidi_transmit() race-free · 06ab3003
      Takashi Iwai authored
      A kernel WARNING in snd_rawmidi_transmit_ack() is triggered by
      syzkaller fuzzer:
        WARNING: CPU: 1 PID: 20739 at sound/core/rawmidi.c:1136
      Call Trace:
       [<     inline     >] __dump_stack lib/dump_stack.c:15
       [<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
       [<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
       [<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
       [<ffffffff84f80bd5>] snd_rawmidi_transmit_ack+0x275/0x400 sound/core/rawmidi.c:1136
       [<ffffffff84fdb3c1>] snd_virmidi_output_trigger+0x4b1/0x5a0 sound/core/seq/seq_virmidi.c:163
       [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
       [<ffffffff84f87ed9>] snd_rawmidi_kernel_write1+0x549/0x780 sound/core/rawmidi.c:1223
       [<ffffffff84f89fd3>] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1273
       [<ffffffff817b0323>] __vfs_write+0x113/0x480 fs/read_write.c:528
       [<ffffffff817b1db7>] vfs_write+0x167/0x4a0 fs/read_write.c:577
       [<     inline     >] SYSC_write fs/read_write.c:624
       [<ffffffff817b50a1>] SyS_write+0x111/0x220 fs/read_write.c:616
       [<ffffffff86336c36>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185
      
      Also a similar warning is found but in another path:
      Call Trace:
       [<     inline     >] __dump_stack lib/dump_stack.c:15
       [<ffffffff82be2c0d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
       [<ffffffff81355139>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
       [<ffffffff81355369>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
       [<ffffffff8527e69a>] rawmidi_transmit_ack+0x24a/0x3b0 sound/core/rawmidi.c:1133
       [<ffffffff8527e851>] snd_rawmidi_transmit_ack+0x51/0x80 sound/core/rawmidi.c:1163
       [<ffffffff852d9046>] snd_virmidi_output_trigger+0x2b6/0x570 sound/core/seq/seq_virmidi.c:185
       [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
       [<ffffffff85285a0b>] snd_rawmidi_kernel_write1+0x4bb/0x760 sound/core/rawmidi.c:1252
       [<ffffffff85287b73>] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1302
       [<ffffffff817ba5f3>] __vfs_write+0x113/0x480 fs/read_write.c:528
       [<ffffffff817bc087>] vfs_write+0x167/0x4a0 fs/read_write.c:577
       [<     inline     >] SYSC_write fs/read_write.c:624
       [<ffffffff817bf371>] SyS_write+0x111/0x220 fs/read_write.c:616
       [<ffffffff86660276>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185
      
      In the former case, the reason is that virmidi has an open code
      calling snd_rawmidi_transmit_ack() with the value calculated outside
      the spinlock.   We may use snd_rawmidi_transmit() in a loop just for
      consuming the input data, but even there, there is a race between
      snd_rawmidi_transmit_peek() and snd_rawmidi_tranmit_ack().
      
      Similarly in the latter case, it calls snd_rawmidi_transmit_peek() and
      snd_rawmidi_tranmit_ack() separately without protection, so they are
      racy as well.
      
      The patch tries to address these issues by the following ways:
      - Introduce the unlocked versions of snd_rawmidi_transmit_peek() and
        snd_rawmidi_transmit_ack() to be called inside the explicit lock.
      - Rewrite snd_rawmidi_transmit() to be race-free (the former case).
      - Make the split calls (the latter case) protected in the rawmidi spin
        lock.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+YPq1+cYLkadwjWa5XjzF1_Vki1eHnVn-Lm0hzhSpu5PA@mail.gmail.com
      BugLink: http://lkml.kernel.org/r/CACT4Y+acG4iyphdOZx47Nyq_VHGbpJQK-6xNpiqUjaZYqsXOGw@mail.gmail.comReported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Tested-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      06ab3003
  2. 22 Nov, 2015 1 commit
  3. 02 Feb, 2015 1 commit
  4. 21 Feb, 2014 1 commit
  5. 02 Oct, 2012 1 commit
  6. 14 Jun, 2011 1 commit
  7. 10 Nov, 2009 1 commit
  8. 09 Mar, 2009 1 commit
  9. 16 Oct, 2007 1 commit
  10. 22 Jun, 2006 1 commit
  11. 22 Mar, 2006 1 commit
  12. 03 Jan, 2006 2 commits
  13. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4