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| author | Takashi Sakamoto <o-takashi@sakamocchi.jp> | 2015-05-22 23:00:50 +0900 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2015-05-23 09:13:18 +0200 |
| commit | a2064710ba2b38a4f07c1b273c389b70b14b2d18 (patch) | |
| tree | 4c4e0f577c796bdf2976f0bcf5bbc44ba781cbd5 /sound/firewire/amdtp.h | |
| parent | 181a152a09ccbf977ea69405cde4d87b5585de6c (diff) | |
| download | linux-a2064710ba2b38a4f07c1b273c389b70b14b2d18.tar.bz2 | |
ALSA: firewire-lib: add buffer-over-run protection at receiving more data blocks than expected
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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/firewire/amdtp.h')
| -rw-r--r-- | sound/firewire/amdtp.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h index 8a03a91e728b..26b909329e54 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, }; /** |