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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Takashi Iwai <tiwai@suse.de>,
        Mark Brown <broonie@kernel.org>
Subject: [PATCH 5.15 117/244] ASoC: SOF: debug: Fix potential buffer overflow by snprintf()
Date:   Tue, 23 Aug 2022 10:24:36 +0200
Message-Id: <20220823080102.925360091@linuxfoundation.org>
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From: Takashi Iwai <tiwai@suse.de>

commit 1eb123ce985e6cf302ac6e3f19862d132d86fa8f upstream.

snprintf() returns the would-be-filled size when the string overflows
the given buffer size, hence using this value may result in the buffer
overflow (although it's unrealistic).

This patch replaces with a safer version, scnprintf() for papering
over such a potential issue.

Fixes: 5b10b6298921 ("ASoC: SOF: Add `memory_info` file to debugfs")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20220801165420.25978-3-tiwai@suse.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/soc/sof/debug.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/sound/soc/sof/debug.c
+++ b/sound/soc/sof/debug.c
@@ -668,9 +668,9 @@ static int memory_info_update(struct snd
 	}
 
 	for (i = 0, len = 0; i < reply->num_elems; i++) {
-		ret = snprintf(buf + len, buff_size - len, "zone %d.%d used %#8x free %#8x\n",
-			       reply->elems[i].zone, reply->elems[i].id,
-			       reply->elems[i].used, reply->elems[i].free);
+		ret = scnprintf(buf + len, buff_size - len, "zone %d.%d used %#8x free %#8x\n",
+				reply->elems[i].zone, reply->elems[i].id,
+				reply->elems[i].used, reply->elems[i].free);
 		if (ret < 0)
 			goto error;
 		len += ret;