ecu: fix alignment of fr_ecu_state
The member data[0] in struct osmo_ecu_state is used as an anchor to
attach private structs for a concrete ECU implementation. This works by
allocating more memory then struct osmo_ecu_state actually needs and
then using the excess memory to store the private struct of the concrete
ECU implementation.
However, this poses a problem since data[0] is at the end of the struct
it may land in an unaligned position. This also means that the struct we
store there is also unaligned.
We should fix this enclosing the public struct osmo_ecu_state into our
private struct fr_ecu_state. Then we can use container_of to cast from
osmo_ecu_state to fr_ecu_state and correct alignment is ensured as well.
Related: OS#6286
Change-Id: I28672856e8e8f47e04ffe09ee3e07b577108cdc7
diff --git a/src/codec/ecu_fr.c b/src/codec/ecu_fr.c
index adde03e..45ba0cc 100644
--- a/src/codec/ecu_fr.c
+++ b/src/codec/ecu_fr.c
@@ -71,6 +71,7 @@
#include <osmocom/codec/codec.h>
#include <osmocom/codec/ecu.h>
+#include <osmocom/core/linuxlist.h>
/* See TS 46.011, Chapter 6 Example solution */
#define GSM611_XMAXC_REDUCE 4
@@ -89,6 +90,7 @@
};
struct fr_ecu_state {
+ struct osmo_ecu_state ecu_state;
enum ecu_principal_state pr_state;
uint8_t speech_frame[GSM_FR_BYTES];
uint8_t sid_prefix[SID_PREFIX_LEN];
@@ -283,27 +285,25 @@
static struct osmo_ecu_state *ecu_fr_init(void *ctx, enum osmo_ecu_codec codec)
{
- struct osmo_ecu_state *st;
struct fr_ecu_state *fr;
- size_t size = sizeof(*st) + sizeof(*fr);
- st = talloc_named_const(ctx, size, "ecu_state_FR");
- if (!st)
- return NULL;
-
- memset(st, 0, size);
- st->codec = codec;
- fr = (struct fr_ecu_state *) &st->data;
+ fr = talloc_zero(ctx, struct fr_ecu_state);
+ fr->ecu_state.codec = codec;
fr->pr_state = STATE_NO_DATA;
osmo_prbs_state_init(&fr->prng, &osmo_prbs15);
- return st;
+ return (struct osmo_ecu_state *) fr;
+}
+
+static inline struct fr_ecu_state *_osmo_ecu_state_get_fr(struct osmo_ecu_state *st)
+{
+ return (struct fr_ecu_state *)container_of(st, struct fr_ecu_state, ecu_state);
}
static int ecu_fr_frame_in(struct osmo_ecu_state *st, bool bfi, const uint8_t *frame,
unsigned int frame_bytes)
{
- struct fr_ecu_state *fr = (struct fr_ecu_state *) &st->data;
+ struct fr_ecu_state *fr = _osmo_ecu_state_get_fr(st);
if (bfi)
return 0;
@@ -318,7 +318,7 @@
static int ecu_fr_frame_out(struct osmo_ecu_state *st, uint8_t *frame_out)
{
- struct fr_ecu_state *fr = (struct fr_ecu_state *) &st->data;
+ struct fr_ecu_state *fr = _osmo_ecu_state_get_fr(st);
fr_ecu_output(fr, frame_out);
return GSM_FR_BYTES;
@@ -326,7 +326,7 @@
static bool ecu_fr_is_dtx_pause(struct osmo_ecu_state *st)
{
- struct fr_ecu_state *fr = (struct fr_ecu_state *) &st->data;
+ struct fr_ecu_state *fr = _osmo_ecu_state_get_fr(st);
return fr->last_input_was_sid;
}