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(). Added a check in fdtv_ca_pmt() to
prevent that.
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Luo Likang <luolikang@xxxxxxxxxxx>
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
RESEND: this patch got lost somehow.
v2: Change the limit in fdtv_ca_pmt() from "sizeof(msg->msg) - 4" to
"sizeof(msg->msg) - data_pos".
Oh, another thing is the data_length calculation in fdtv_ca_pmt() seems
very suspicous. Reading more than 4 bytes in the loop will lead to
shift wrapping.
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 2bf9467b917d..71991f8638e6 100644
--- a/drivers/media/firewire/firedtv-avc.c
+++ b/drivers/media/firewire/firedtv-avc.c
@@ -1165,7 +1165,11 @@ 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++];
@@ -1177,13 +1181,17 @@ 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 9363d005e2b6..2d6992ac5dd6 100644
--- a/drivers/media/firewire/firedtv-ci.c
+++ b/drivers/media/firewire/firedtv-ci.c
@@ -134,6 +134,8 @@ 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);
}
--
2.30.2
