Skip to content

in_forward: fix connection release on pause memory corruption [Backport to 4.0] #11182

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 19, 2025
+66 −6
Merged

in_forward: fix connection release on pause memory corruption [Backport to 4.0] #11182

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
27 changes: 26 additions & 1 deletion plugins/in_forward/fw.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -124,28 +124,37 @@ static int fw_unix_create(struct flb_in_fw_config *ctx)
static int in_fw_collect(struct flb_input_instance *ins,
struct flb_config *config, void *in_context)
{
int state_backup;
struct flb_connection *connection;
struct fw_conn *conn;
struct flb_in_fw_config *ctx;

ctx = in_context;

state_backup = ctx->state;
ctx->state = FW_INSTANCE_STATE_ACCEPTING_CLIENT;

connection = flb_downstream_conn_get(ctx->downstream);

if (connection == NULL) {
flb_plg_error(ctx->ins, "could not accept new connection");
ctx->state = state_backup;

return -1;
}

if (!config->is_ingestion_active) {
flb_downstream_conn_release(connection);
ctx->state = state_backup;

return -1;
}

if(ctx->is_paused) {
flb_downstream_conn_release(connection);
flb_plg_trace(ins, "TCP connection will be closed FD=%i", connection->fd);
ctx->state = state_backup;

return -1;
}

Expand All @@ -154,9 +163,17 @@ static int in_fw_collect(struct flb_input_instance *ins,
conn = fw_conn_add(connection, ctx);
if (!conn) {
flb_downstream_conn_release(connection);
ctx->state = state_backup;

return -1;
}

ctx->state = state_backup;

if (ctx->state == FW_INSTANCE_STATE_PAUSED) {
fw_conn_del_all(ctx);
Comment on lines +171 to +174
Copy link

@chatgpt-codex-connector chatgpt-codex-connector bot Nov 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

P1 Badge Prevent overwriting paused state after accepting a client

The collector backs up the plugin state, switches it to FW_INSTANCE_STATE_ACCEPTING_CLIENT, and at the end unconditionally restores the backup before checking for a pause. If in_fw_pause() fires while a connection is being accepted it sets ctx->state to FW_INSTANCE_STATE_PAUSED so it can close connections later, but these lines overwrite that pause state back to the old value and the subsequent fw_conn_del_all(ctx) guard never runs. As a result existing connections remain active and continue ingesting while the input is paused, defeating backpressure. The state should only be restored when it is still ACCEPTING_CLIENT; if the state has become PAUSED we should keep that state and trigger cleanup similar to fw_conn_event.

Useful? React with 👍 / 👎.

}

return 0;
}

Expand Down Expand Up @@ -263,6 +280,7 @@ static int in_fw_init(struct flb_input_instance *ins,
return -1;
}

ctx->state = FW_INSTANCE_STATE_RUNNING;
ctx->coll_fd = -1;
ctx->ins = ins;
mk_list_init(&ctx->connections);
Expand Down Expand Up @@ -386,7 +404,10 @@ static void in_fw_pause(void *data, struct flb_config *config)
return;
}

fw_conn_del_all(ctx);
if (ctx->state == FW_INSTANCE_STATE_RUNNING) {
fw_conn_del_all(ctx);
}

ctx->is_paused = FLB_TRUE;
ret = pthread_mutex_unlock(&ctx->conn_mutex);
if (ret != 0) {
Expand All @@ -406,6 +427,8 @@ static void in_fw_pause(void *data, struct flb_config *config)
if (config->is_ingestion_active == FLB_FALSE) {
fw_conn_del_all(ctx);
}

ctx->state = FW_INSTANCE_STATE_PAUSED;
}

static void in_fw_resume(void *data, struct flb_config *config) {
Expand All @@ -427,6 +450,8 @@ static void in_fw_resume(void *data, struct flb_config *config) {
flb_plg_error(ctx->ins, "cannot unlock collector mutex");
return;
}

ctx->state = FW_INSTANCE_STATE_RUNNING;
}
}

Expand Down
8 changes: 8 additions & 0 deletions plugins/in_forward/fw.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,12 @@
#include <fluent-bit/flb_log_event_decoder.h>
#include <fluent-bit/flb_log_event_encoder.h>

#define FW_INSTANCE_STATE_RUNNING 0
#define FW_INSTANCE_STATE_ACCEPTING_CLIENT 1
#define FW_INSTANCE_STATE_PROCESSING_PACKET 2
#define FW_INSTANCE_STATE_PAUSED 3


enum {
FW_HANDSHAKE_HELO = 1,
FW_HANDSHAKE_PINGPONG = 2,
Expand Down Expand Up @@ -76,6 +82,8 @@ struct flb_in_fw_config {

pthread_mutex_t conn_mutex;

int state;

/* Plugin is paused */
int is_paused;
};
Expand Down
37 changes: 32 additions & 5 deletions plugins/in_forward/fw_conn.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,7 @@
#include "fw_prot.h"
#include "fw_conn.h"

/* Callback invoked every time an event is triggered for a connection */
int fw_conn_event(void *data)
static int fw_conn_event_internal(struct flb_connection *connection)
{
int ret;
int bytes;
Expand All @@ -39,9 +38,6 @@ int fw_conn_event(void *data)
struct fw_conn *conn;
struct mk_event *event;
struct flb_in_fw_config *ctx;
struct flb_connection *connection;

connection = (struct flb_connection *) data;

conn = connection->user_data;

Expand Down Expand Up @@ -127,6 +123,37 @@ int fw_conn_event(void *data)
return 0;
}

/* Callback invoked every time an event is triggered for a connection */
int fw_conn_event(void *data)
{
struct flb_in_fw_config *ctx;
struct fw_conn *conn;
int result;
struct flb_connection *connection;
int state_backup;

connection = (struct flb_connection *) data;

conn = connection->user_data;

ctx = conn->ctx;

state_backup = ctx->state;

ctx->state = FW_INSTANCE_STATE_PROCESSING_PACKET;

result = fw_conn_event_internal(connection);

if (ctx->state == FW_INSTANCE_STATE_PROCESSING_PACKET) {
ctx->state = state_backup;
}
else if (ctx->state == FW_INSTANCE_STATE_PAUSED) {
fw_conn_del_all(ctx);
}

return result;
}

/* Create a new Forward request instance */
struct fw_conn *fw_conn_add(struct flb_connection *connection, struct flb_in_fw_config *ctx)
{
Expand Down
Loading