ALSA: dice: fix buffer overflow in detect_stream_formats()

The function detect_stream_formats() reads the stream_count value directly
from a FireWire device without validating it. This can lead to
out-of-bounds writes when a malicious device provides a stream_count value
greater than MAX_STREAMS.

Fix by applying the same validation to both TX and RX stream counts in
detect_stream_formats().

Reported-by: Yuhao Jiang <danisjiang@gmail.com>
Reported-by: Junrui Luo <moonafterrain@outlook.com>
Fixes: 58579c056c1c ("ALSA: dice: use extended protocol to detect available stream formats")
Cc: stable@vger.kernel.org
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
Link: https://patch.msgid.link/SYBPR01MB7881B043FC68B4C0DA40B73DAFDCA@SYBPR01MB7881.ausprd01.prod.outlook.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/dice/dice-extension.c b/sound/firewire/dice/dice-extension.c
index 02f4a8318e38e7309da42b3274a59fee95d8349f..48bfb3ad93ce55061305d4a13f4caf4b872621cb 100644 (file)
--- a/sound/firewire/dice/dice-extension.c
+++ b/sound/firewire/dice/dice-extension.c
@@ -116,7 +116,7 @@ static int detect_stream_formats(struct snd_dice *dice, u64 section_addr)
                        break;
 
                base_offset += EXT_APP_STREAM_ENTRIES;
-               stream_count = be32_to_cpu(reg[0]);
+               stream_count = min_t(unsigned int, be32_to_cpu(reg[0]), MAX_STREAMS);
                err = read_stream_entries(dice, section_addr, base_offset,
                                          stream_count, mode,
                                          dice->tx_pcm_chs,
@@ -125,7 +125,7 @@ static int detect_stream_formats(struct snd_dice *dice, u64 section_addr)
                        break;
 
                base_offset += stream_count * EXT_APP_STREAM_ENTRY_SIZE;
-               stream_count = be32_to_cpu(reg[1]);
+               stream_count = min_t(unsigned int, be32_to_cpu(reg[1]), MAX_STREAMS);
                err = read_stream_entries(dice, section_addr, base_offset,
                                          stream_count,
                                          mode, dice->rx_pcm_chs,