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 --- sound/firewire/amdtp.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c index 2b3e8b1..7bb988f 100644 --- a/sound/firewire/amdtp.c +++ b/sound/firewire/amdtp.c @@ -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; }