On Mon, Jan 24, 2022 at 07:35:29PM +0100, Ben Hutchings wrote:

From: Dan Carpenter dan.carpenter@oracle.com

commit 35d2969ea3c7d32aee78066b1f3cf61a0d935a4e upstream.

The bounds checking in avc_ca_pmt() is not strict enough. It should be checking "read_pos + 4" because it's reading 5 bytes. If the "es_info_length" is non-zero then it reads a 6th byte so there needs to be an additional check for that.

I also added checks for the "write_pos". I don't think these are required because "read_pos" and "write_pos" are tied together so checking one ought to be enough. But they make the code easier to understand for me. The check on write_pos is:

if (write_pos + 4 >= sizeof(c->operand) - 4) {

The first "+ 4" is because we're writing 5 bytes and the last " - 4" is to leave space for the CRC.

The other problem is that "length" can be invalid. It comes from "data_length" in fdtv_ca_pmt().

Cc: stable@vger.kernel.org Reported-by: Luo Likang luolikang@nsfocus.com Signed-off-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org [bwh: Backported to 4.9: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk

---

drivers/media/firewire/firedtv-avc.c | 14 +++++++++++--- drivers/media/firewire/firedtv-ci.c | 2 ++ 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/media/firewire/firedtv-avc.c b/drivers/media/firewire/firedtv-avc.c index 280b5ffea592..3a373711f5ad 100644 --- a/drivers/media/firewire/firedtv-avc.c +++ b/drivers/media/firewire/firedtv-avc.c @@ -1169,7 +1169,11 @@ int avc_ca_pmt(struct firedtv *fdtv, char *msg, int length) read_pos += program_info_length; write_pos += program_info_length; }

• while (read_pos < length) {

• while (read_pos + 4 < length) {

• if (write_pos + 4 >= sizeof(c->operand) - 4) {
  

• 	ret = -EINVAL;
  

• 	goto out;
  

• }
  

  c->operand[write_pos++] = msg[read_pos++]; c->operand[write_pos++] = msg[read_pos++]; c->operand[write_pos++] = msg[read_pos++];

@@ -1181,13 +1185,17 @@ int avc_ca_pmt(struct firedtv *fdtv, char *msg, int length) c->operand[write_pos++] = es_info_length >> 8; c->operand[write_pos++] = es_info_length & 0xff; if (es_info_length > 0) {

• 	if (read_pos >= length) {
  

• 		ret = -EINVAL;
  

• 		goto out;
  

• 	}
  pmt_cmd_id = msg[read_pos++];
  if (pmt_cmd_id != 1 && pmt_cmd_id != 4)
  	dev_err(fdtv->device, "invalid pmt_cmd_id %d "
  		"at stream level\n", pmt_cmd_id);
  

• 	if (es_info_length > sizeof(c->operand) - 4 -
  

• 			     write_pos) {
  

• 	if (es_info_length > sizeof(c->operand) - 4 - write_pos ||
  

• 	    es_info_length > length - read_pos) {
  	ret = -EINVAL;
  	goto out;
  }
  

diff --git a/drivers/media/firewire/firedtv-ci.c b/drivers/media/firewire/firedtv-ci.c index edbb30fdd9d9..93fb4b7312af 100644 --- a/drivers/media/firewire/firedtv-ci.c +++ b/drivers/media/firewire/firedtv-ci.c @@ -138,6 +138,8 @@ static int fdtv_ca_pmt(struct firedtv *fdtv, void *arg) } else { data_length = msg->msg[3]; }

• if (data_length > sizeof(msg->msg) - data_pos)

• return -EINVAL;
  

return avc_ca_pmt(fdtv, &msg->msg[data_pos], data_length); }

All of the 4.9 backports now queued up,t hanks.

greg k-h