Merged in stable-2.12 and stable-2.11.
Thanks!
Jérémie
----- Original Message -----
> From: "Mathieu Desnoyers" <mathieu.desnoy...@efficios.com>
> To: jga...@efficios.com
> Cc: "lttng-dev" <lttng-dev@lists.lttng.org>, "Mathieu Desnoyers"
> <mathieu.desnoy...@efficios.com>
> Sent: Thursday, May 27, 2021 5:11:22 PM
> Subject: [PATCH lttng-tools stable-2.12] Fix: list_lttng_agent_events:
> unbalanced RCU read-side lock on error
> The error label jumps to the end label which releases the RCU read-side
> lock. There are many error paths in this function which goto error
> without holding the RCU read-side lock, thus causing unbalanced RCU
> read-side lock.
>
> There is no point in keeping so short RCU read-side critical sections,
> so cover the entire function with a single read-side critical section.
>
> [ Applies to stable-2.12 and possibly prior versions. Does _not_ apply
> to stable-2.13+. ]
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
> Change-Id: I5b20c229a5df22d22ecfdc64dbbb87ee118649d2
> ---
> src/bin/lttng-sessiond/cmd.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
> index b608df1e1..eb5da1b76 100644
> --- a/src/bin/lttng-sessiond/cmd.c
> +++ b/src/bin/lttng-sessiond/cmd.c
> @@ -510,7 +510,6 @@ static int list_lttng_agent_events(struct agent *agt,
>
> rcu_read_lock();
> nb_event = lttng_ht_get_count(agt->events);
> - rcu_read_unlock();
> if (nb_event == 0) {
> ret = nb_event;
> *total_size = 0;
> @@ -524,7 +523,6 @@ static int list_lttng_agent_events(struct agent *agt,
> * This is only valid because the commands which add events are
> * processed in the same thread as the listing.
> */
> - rcu_read_lock();
> cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
> ret = increment_extended_len(event->filter_expression, NULL,
> NULL,
> &extended_len);
> @@ -534,7 +532,6 @@ static int list_lttng_agent_events(struct agent *agt,
> goto error;
> }
> }
> - rcu_read_unlock();
>
> *total_size = nb_event * sizeof(*tmp_events) + extended_len;
> tmp_events = zmalloc(*total_size);
> @@ -547,7 +544,6 @@ static int list_lttng_agent_events(struct agent *agt,
> extended_at = ((uint8_t *) tmp_events) +
> nb_event * sizeof(struct lttng_event);
>
> - rcu_read_lock();
> cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
> strncpy(tmp_events[i].name, event->name,
> sizeof(tmp_events[i].name));
> tmp_events[i].name[sizeof(tmp_events[i].name) - 1] = '\0';
> --
> 2.17.1
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