[PATCH 4.4 003/113] ALSA: hda: Use scnprintf() for printing texts for sysfs/procfs

[Greg Kroah-Hartman]

From: Takashi Iwai <tiwai@xxxxxxx>

commit 44eeb081b8630bb3ad3cd381d1ae1831463e48bb upstream.

Some code in HD-audio driver calls snprintf() in a loop and still
expects that the return value were actually written size, while
snprintf() returns the expected would-be length instead.  When the
given buffer limit were small, this leads to a buffer overflow.

Use scnprintf() for addressing those issues.  It returns the actually
written size unlike snprintf().

Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200218091409.27162-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 sound/pci/hda/hda_codec.c |    2 +-
 sound/pci/hda/hda_eld.c   |    2 +-
 sound/pci/hda/hda_sysfs.c |    4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -4098,7 +4098,7 @@ void snd_print_pcm_bits(int pcm, char *b
 
 	for (i = 0, j = 0; i < ARRAY_SIZE(bits); i++)
 		if (pcm & (AC_SUPPCM_BITS_8 << i))
-			j += snprintf(buf + j, buflen - j,  " %d", bits[i]);
+			j += scnprintf(buf + j, buflen - j,  " %d", bits[i]);
 
 	buf[j] = '\0'; /* necessary when j == 0 */
 }
--- a/sound/pci/hda/hda_eld.c
+++ b/sound/pci/hda/hda_eld.c
@@ -385,7 +385,7 @@ static void hdmi_print_pcm_rates(int pcm
 
 	for (i = 0, j = 0; i < ARRAY_SIZE(alsa_rates); i++)
 		if (pcm & (1 << i))
-			j += snprintf(buf + j, buflen - j,  " %d",
+			j += scnprintf(buf + j, buflen - j,  " %d",
 				alsa_rates[i]);
 
 	buf[j] = '\0'; /* necessary when j == 0 */
--- a/sound/pci/hda/hda_sysfs.c
+++ b/sound/pci/hda/hda_sysfs.c
@@ -221,7 +221,7 @@ static ssize_t init_verbs_show(struct de
 	mutex_lock(&codec->user_mutex);
 	for (i = 0; i < codec->init_verbs.used; i++) {
 		struct hda_verb *v = snd_array_elem(&codec->init_verbs, i);
-		len += snprintf(buf + len, PAGE_SIZE - len,
+		len += scnprintf(buf + len, PAGE_SIZE - len,
 				"0x%02x 0x%03x 0x%04x\n",
 				v->nid, v->verb, v->param);
 	}
@@ -271,7 +271,7 @@ static ssize_t hints_show(struct device
 	mutex_lock(&codec->user_mutex);
 	for (i = 0; i < codec->hints.used; i++) {
 		struct hda_hint *hint = snd_array_elem(&codec->hints, i);
-		len += snprintf(buf + len, PAGE_SIZE - len,
+		len += scnprintf(buf + len, PAGE_SIZE - len,
 				"%s = %s\n", hint->key, hint->val);
 	}
 	mutex_unlock(&codec->user_mutex);