Commit 31ea49ba authored by Takashi Sakamoto's avatar Takashi Sakamoto Committed by Takashi Iwai
Browse files

ALSA: firewire-lib: fix buffer-over-run when detecting packet discontinuity 



When detecting packet discontinuity, handle_in_packet() returns minus value
and this value is assigned to unsigned int variable, then the variable has
huge value. As a result, the variable causes buffer-over-run in
handle_out_packet(). This brings invalid page request and system hangup.

This commit fixes the bug to add a new argument into handle_in_packet()
and the number of handled data blocks is assignd to it. The function
return value is just used to check error.

I also considered to change the type of local variable to 'int' in
in_stream_callback(). This idea is based on type-conversion in C standard,
while it may cause future problems when adding more works. Thus, I dropped
this idea.

Fixes: 6fc6b9ce('ALSA: firewire-lib: pass the number of data blocks in incoming packets to outgoing packets')
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 0d769a52

sound/firewire/amdtp.c

+16 −16
Original line number Diff line number Diff line
@@ -688,10 +688,10 @@ static int handle_out_packet(struct amdtp_stream *s, unsigned int data_blocks, 
}



static int handle_in_packet(struct amdtp_stream *s,

			    unsigned int payload_quadlets, __be32 *buffer)

			    unsigned int payload_quadlets, __be32 *buffer,

			    unsigned int *data_blocks)

{

	u32 cip_header[2];

	unsigned int data_blocks;

	unsigned int data_block_quadlets, data_block_counter, dbc_interval;

	struct snd_pcm_substream *pcm = NULL;

	bool lost;
@@ -709,7 +709,7 @@ static int handle_in_packet(struct amdtp_stream *s, 
		dev_info_ratelimited(&s->unit->device,

				"Invalid CIP header for AMDTP: %08X:%08X\n",

				cip_header[0], cip_header[1]);

		data_blocks = 0;

		*data_blocks = 0;

		goto end;

	}
@@ -717,7 +717,7 @@ static int handle_in_packet(struct amdtp_stream *s, 
	if (payload_quadlets < 3 ||

	    ((cip_header[1] & CIP_FDF_MASK) ==

				(AMDTP_FDF_NO_DATA << CIP_FDF_SHIFT))) {

		data_blocks = 0;

		*data_blocks = 0;

	} else {

		data_block_quadlets =

			(cip_header[0] & CIP_DBS_MASK) >> CIP_DBS_SHIFT;
@@ -731,12 +731,12 @@ static int handle_in_packet(struct amdtp_stream *s, 
		if (s->flags & CIP_WRONG_DBS)

			data_block_quadlets = s->data_block_quadlets;



		data_blocks = (payload_quadlets - 2) / data_block_quadlets;

		*data_blocks = (payload_quadlets - 2) / data_block_quadlets;

	}



	/* Check data block counter continuity */

	data_block_counter = cip_header[0] & CIP_DBC_MASK;

	if (data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&

	if (*data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&

	    s->data_block_counter != UINT_MAX)

		data_block_counter = s->data_block_counter;
@@ -746,10 +746,10 @@ static int handle_in_packet(struct amdtp_stream *s, 
	} else if (!(s->flags & CIP_DBC_IS_END_EVENT)) {

		lost = data_block_counter != s->data_block_counter;

	} else {

		if ((data_blocks > 0) && (s->tx_dbc_interval > 0))

		if ((*data_blocks > 0) && (s->tx_dbc_interval > 0))

			dbc_interval = s->tx_dbc_interval;

		else

			dbc_interval = data_blocks;

			dbc_interval = *data_blocks;



		lost = data_block_counter !=

		       ((s->data_block_counter + dbc_interval) & 0xff);
@@ -762,30 +762,30 @@ static int handle_in_packet(struct amdtp_stream *s, 
		return -EIO;

	}



	if (data_blocks > 0) {

	if (*data_blocks > 0) {

		buffer += 2;



		pcm = ACCESS_ONCE(s->pcm);

		if (pcm)

			s->transfer_samples(s, pcm, buffer, data_blocks);

			s->transfer_samples(s, pcm, buffer, *data_blocks);



		if (s->midi_ports)

			read_midi_messages(s, buffer, data_blocks);

			read_midi_messages(s, buffer, *data_blocks);

	}



	if (s->flags & CIP_DBC_IS_END_EVENT)

		s->data_block_counter = data_block_counter;

	else

		s->data_block_counter =

				(data_block_counter + data_blocks) & 0xff;

				(data_block_counter + *data_blocks) & 0xff;

end:

	if (queue_in_packet(s) < 0)

		return -EIO;



	if (pcm)

		update_pcm_pointers(s, pcm, data_blocks);

		update_pcm_pointers(s, pcm, *data_blocks);



	return data_blocks;

	return 0;

}



static void out_stream_callback(struct fw_iso_context *context, u32 cycle,
@@ -853,8 +853,8 @@ static void in_stream_callback(struct fw_iso_context *context, u32 cycle, 
			break;

		}



		data_blocks = handle_in_packet(s, payload_quadlets, buffer);

		if (data_blocks < 0) {

		if (handle_in_packet(s, payload_quadlets, buffer,

							&data_blocks) < 0) {

			s->packet_index = -1;

			break;

		}

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