In IEC 61883-6, the number of data blocks in a packet is limited up to the value of SYT_INTERVAL. Current implementation is compliant to the limitation, while it can cause buffer-over-run when the value of dbs field in received packet is illegally large.
This commit adds a validator to detect such illegal packets to prevent the buffer-over-run. Actually, the buffer is aligned to the size of memory page, thus this issue hardly causes system errors due to the room to page alignment, as long as a few packets includes such jumbo payload; i.e. a packet to several received packets.
Here, Behringer F-Control Audio 202 (based on OXFW 960) has a quirk to postpone transferring isochronous packet till finish handling any asynchronous packets. In this case, this model is lazy, transfers no packets according to several cycle-start packets. After finishing, this model pushes required data in next isochronous packet. As a result, the packet include more data blocks than IEC 61883-6 defines.
To continue to support this model, this commit adds a new flag to extend the length of calculated payload. This flag allows the size of payload 5 times as large as IEC 61883-6 defines. As a result, packets from this model passed the validator successfully.
Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp --- sound/firewire/amdtp.c | 21 +++++++++++++++++++-- sound/firewire/amdtp.h | 4 ++++ sound/firewire/oxfw/oxfw-stream.c | 10 ++++++++-- 3 files changed, 31 insertions(+), 4 deletions(-)
diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c index d882ca5..4eb8dc9 100644 --- a/sound/firewire/amdtp.c +++ b/sound/firewire/amdtp.c @@ -255,7 +255,12 @@ EXPORT_SYMBOL(amdtp_stream_set_parameters); */ unsigned int amdtp_stream_get_max_payload(struct amdtp_stream *s) { - return 8 + s->syt_interval * s->data_block_quadlets * 4; + unsigned int multiplier = 1; + + if (s->flags & CIP_JUMBO_PAYLOAD) + multiplier = 5; + + return 8 + s->syt_interval * s->data_block_quadlets * 4 * multiplier; } EXPORT_SYMBOL(amdtp_stream_get_max_payload);
@@ -811,12 +816,16 @@ static void in_stream_callback(struct fw_iso_context *context, u32 cycle, void *private_data) { struct amdtp_stream *s = private_data; - unsigned int p, syt, packets, payload_quadlets; + unsigned int p, syt, packets; + unsigned int payload_quadlets, max_payload_quadlets; __be32 *buffer, *headers = header;
/* The number of packets in buffer */ packets = header_length / IN_PACKET_HEADER_SIZE;
+ /* For buffer-over-run prevention. */ + max_payload_quadlets = amdtp_stream_get_max_payload(s) / 4; + for (p = 0; p < packets; p++) { if (s->packet_index < 0) break; @@ -832,6 +841,14 @@ static void in_stream_callback(struct fw_iso_context *context, u32 cycle, /* The number of quadlets in this packet */ payload_quadlets = (be32_to_cpu(headers[p]) >> ISO_DATA_LENGTH_SHIFT) / 4; + if (payload_quadlets > max_payload_quadlets) { + dev_err(&s->unit->device, + "Detect jumbo payload: %02x %02x\n", + payload_quadlets, max_payload_quadlets); + s->packet_index = -1; + break; + } + handle_in_packet(s, payload_quadlets, buffer); }
diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h index 8a03a91..26b9093 100644 --- a/sound/firewire/amdtp.h +++ b/sound/firewire/amdtp.h @@ -29,6 +29,9 @@ * packet is not continuous from an initial value. * @CIP_EMPTY_HAS_WRONG_DBC: Only for in-stream. The value of dbc in empty * packet is wrong but the others are correct. + * @CIP_JUMBO_PAYLOAD: Only for in-stream. The number of data blocks in an + * packet is larger than IEC 61883-6 defines. Current implementation + * allows 5 times as large as IEC 61883-6 defines. */ enum cip_flags { CIP_NONBLOCKING = 0x00, @@ -40,6 +43,7 @@ enum cip_flags { CIP_SKIP_DBC_ZERO_CHECK = 0x20, CIP_SKIP_INIT_DBC_CHECK = 0x40, CIP_EMPTY_HAS_WRONG_DBC = 0x80, + CIP_JUMBO_PAYLOAD = 0x100, };
/** diff --git a/sound/firewire/oxfw/oxfw-stream.c b/sound/firewire/oxfw/oxfw-stream.c index e6757cd..873d40f 100644 --- a/sound/firewire/oxfw/oxfw-stream.c +++ b/sound/firewire/oxfw/oxfw-stream.c @@ -232,9 +232,15 @@ int snd_oxfw_stream_init_simplex(struct snd_oxfw *oxfw, goto end; }
- /* OXFW starts to transmit packets with non-zero dbc. */ + /* + * OXFW starts to transmit packets with non-zero dbc. + * OXFW postpone transferring packets till handling any asynchronous + * packets. As a result, next isochronous packet includes more data + * blocks than IEC 61883-6 defines. + */ if (stream == &oxfw->tx_stream) - oxfw->tx_stream.flags |= CIP_SKIP_INIT_DBC_CHECK; + oxfw->tx_stream.flags |= CIP_SKIP_INIT_DBC_CHECK | + CIP_JUMBO_PAYLOAD; end: return err; }