ALSA: ctxfi: Fix potential OOB access in audio mixer handling

In the audio mixer handling code of ctxfi driver, the conf field is
used as a kind of loop index, and it's referred in the index callbacks
(amixer_index() and sum_index()).

As spotted recently by fuzzers, the current code causes OOB access at
those functions.
| UBSAN: array-index-out-of-bounds in /build/reproducible-path/linux-6.17.8/sound/pci/ctxfi/ctamixer.c:347:48
| index 8 is out of range for type 'unsigned char [8]'

After the analysis, the cause was found to be the lack of the proper
(re-)initialization of conj field.

This patch addresses those OOB accesses by adding the proper
initializations of the loop indices.

Reported-by: Salvatore Bonaccorso <[e-mail]>
Tested-by: Karsten Hohmeier <[e-mail]>
Closes: https://bugs.debian.org/1121535
Cc: <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]/
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/pci/ctxfi/ctamixer.c

···
 
 	/* Set amixer specific operations */
 	amixer->rsc.ops = &amixer_basic_rsc_ops;
+	amixer->rsc.conj = 0;
 	amixer->ops = &amixer_ops;
 	amixer->input = NULL;
 	amixer->sum = NULL;
···
 		return err;
 
 	sum->rsc.ops = &sum_basic_rsc_ops;
+	sum->rsc.conj = 0;
 
 	return 0;
 }