• Takashi Iwai's avatar
    ALSA: seq: Fix UBSAN warning at SNDRV_SEQ_IOCTL_QUERY_NEXT_CLIENT ioctl · c9a4c638
    Takashi Iwai authored
    The kernel may spew a WARNING with UBSAN undefined behavior at
    handling ALSA sequencer ioctl SNDRV_SEQ_IOCTL_QUERY_NEXT_CLIENT:
    
    UBSAN: Undefined behaviour in sound/core/seq/seq_clientmgr.c:2007:14
    signed integer overflow:
    2147483647 + 1 cannot be represented in type 'int'
    Call Trace:
     __dump_stack lib/dump_stack.c:77 [inline]
     dump_stack+0x122/0x1c8 lib/dump_stack.c:113
     ubsan_epilogue+0x12/0x86 lib/ubsan.c:159
     handle_overflow+0x1c2/0x21f lib/ubsan.c:190
      __ubsan_handle_add_overflow+0x2a/0x31 lib/ubsan.c:198
     snd_seq_ioctl_query_next_client+0x1ac/0x1d0 sound/core/seq/seq_clientmgr.c:2007
     snd_seq_ioctl+0x264/0x3d0 sound/core/seq/seq_clientmgr.c:2144
     ....
    
    It happens only when INT_MAX is passed there, as we're incrementing it
    unconditionally.  So the fix is trivial, check the value with
    INT_MAX.  Although the bug itself is fairly harmless, it's better to
    fix it so that fuzzers won't hit this again later.
    
    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200211Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    c9a4c638
seq_clientmgr.c 65.8 KB