Re: [PATCH] ALSA: firewire-lib: fix wrong value as length of header for CIP_NO_HEADER case

Re: [PATCH] ALSA: firewire-lib: fix wrong value as length of header for CIP_NO_HEADER case

[Takashi Sakamoto]

On 25/07/24 09:56, Takashi Sakamoto wrote:
> In a commit 1d717123bb1a ("ALSA: firewire-lib: Avoid
> -Wflex-array-member-not-at-end warning"), DEFINE_FLEX() macro was used to
> handle variable length of array for header field in struct fw_iso_packet
> structure. The usage of macro has a side effect that the designated
> initializer assigns the count of array to the given field. Therefore
> CIP_HEADER_QUADLETS (=2) is assigned to struct fw_iso_packet.header,
> while the original designated initializer assigns zero to all fields.
> 
> With CIP_NO_HEADER flag, the change causes invalid length of header in
> isochronous packet for 1394 OHCI IT context. This bug affects all of
> devices supported by ALSA fireface driver; RME Fireface 400, 800, UCX, UFX,
> and 802.
> 
> This commit fixes the bug by replacing it with the alternative version of
> macro which corresponds no initializer.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 1d717123bb1a ("ALSA: firewire-lib: Avoid -Wflex-array-member-not-at-end warning")
> Reported-by: Edmund Raile <edmund.raile@proton.me>
> Closes: https://lore.kernel.org/r/rrufondjeynlkx2lniot26ablsltnynfaq2gnqvbiso7ds32il@qk4r6xps7jh2/
> Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
> ---
>   sound/firewire/amdtp-stream.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
> index d35d0a420ee0..1a163bbcabd7 100644
> --- a/sound/firewire/amdtp-stream.c
> +++ b/sound/firewire/amdtp-stream.c
> @@ -1180,8 +1180,7 @@ static void process_rx_packets(struct fw_iso_context *context, u32 tstamp, size_
>   		(void)fw_card_read_cycle_time(fw_parent_device(s->unit)->card, &curr_cycle_time);
>   	for (i = 0; i < packets; ++i) {
> -		DEFINE_FLEX(struct fw_iso_packet, template, header,
> -			    header_length, CIP_HEADER_QUADLETS);
> +		DEFINE_RAW_FLEX(struct fw_iso_packet, template, header, CIP_HEADER_QUADLETS);
>   		bool sched_irq = false;
>   		build_it_pkt_header(s, desc->cycle, template, pkt_header_length,

Applied to for-linus branch in firewire subsystem tree[1], and would be
sent to mainline today with another patch[2].


[1] https://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394.git/log/?h=for-linus
[2] https://lore.kernel.org/lkml/20240725161648.130404-1-o-takashi@sakamocchi.jp/

Regards

Takashi Sakamoto