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

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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: 6fc6b9ce41c6('ALSA: firewire-lib: pass the number of data blocks in incoming packets to outgoing packets')
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Sakamoto 2015-05-28 00:02:59 +09:00 committed by Takashi Iwai
parent 0d769a523a
commit 31ea49baa1
1 changed files with 16 additions and 16 deletions
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32
sound/firewire/amdtp.c
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@ -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;
}