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lightningd/subd: fix use-after-free, cleanup subd_send_msg unnecessary tal_dup.

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subd_req() needs to get the type before it calls subd_send_msg, because
if it's take() then msg_enqueue() may reallocate.

Which also made me realize that subd_send_message() should not try to dup,
since msg_enqueue() handles that itself.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2017-03-14 10:57:48 +10:30
parent 8ae698d1dc
commit 8a893df951
1 changed files with 5 additions and 4 deletions
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9
lightningd/subd.c
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@ -371,9 +371,7 @@ void subd_send_msg(struct subd *sd, const u8 *msg_out)
{ {
/* We overload STATUS_TRACE for outgoing to mean "send an fd" */ /* We overload STATUS_TRACE for outgoing to mean "send an fd" */
assert(fromwire_peektype(msg_out) != STATUS_TRACE); assert(fromwire_peektype(msg_out) != STATUS_TRACE);
if (!taken(msg_out)) msg_enqueue(&sd->outq, msg_out);
msg_out = tal_dup_arr(sd, u8, msg_out, tal_len(msg_out), 0);
msg_enqueue(&sd->outq, take(msg_out));
} }
void subd_send_fd(struct subd *sd, int fd) void subd_send_fd(struct subd *sd, int fd)
@ -391,11 +389,14 @@ void subd_req_(struct subd *sd,
bool (*replycb)(struct subd *, const u8 *, void *), bool (*replycb)(struct subd *, const u8 *, void *),
void *replycb_data) void *replycb_data)
{ {
/* Grab type now in case msg_out is taken() */
int type = fromwire_peektype(msg_out);
subd_send_msg(sd, msg_out); subd_send_msg(sd, msg_out);
if (fd_out >= 0) if (fd_out >= 0)
subd_send_fd(sd, fd_out); subd_send_fd(sd, fd_out);
add_req(sd, fromwire_peektype(msg_out), replycb, replycb_data, fd_in); add_req(sd, type, replycb, replycb_data, fd_in);
} }
char *opt_subd_debug(const char *optarg, struct lightningd *ld) char *opt_subd_debug(const char *optarg, struct lightningd *ld)