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=200211
Signed-off-by: Takashi Iwai <tiwai@suse.de>
c9a4c63888