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ssh_terminal: fixed managing ssh file descriptors

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Managing ssh event file descriptors was performed from two different
threads which could cause reallocation of structure used in other thread
in a call to 'poll' function.

Splitted initialization to parts and moved ssh event part into ssh loop.

Issue #4095
This commit is contained in:
Tomasz Gajewski 2021-05-18 01:08:28 +02:00 committed by Christian Helmuth
parent 0b641ba581
commit 0507d3f44b
2 changed files with 51 additions and 10 deletions
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41
repos/gems/src/server/ssh_terminal/server.cc
View File

@ -48,16 +48,28 @@ Ssh::Terminal_session::Terminal_session(Genode::Registry<Terminal_session> &reg,
:
Element(reg, *this), conn(conn), _event_loop(event_loop)
{
if (pipe(_fds) ||
ssh_event_add_fd(_event_loop,
_fds[0],
POLLIN,
write_avail_cb,
this) != SSH_OK ) {
if (pipe(_fds)) {
Genode::error("Failed to create wakeup pipe");
throw -1;
}
conn.write_avail_fd = _fds[1];
_state = PIPE_INITIALIZED;
}
void Ssh::Terminal_session::initialize_ssh_event_fds()
{
if (_state != PIPE_INITIALIZED ||
ssh_event_add_fd(_event_loop,
_fds[0],
POLLIN,
write_avail_cb,
this) != SSH_OK) {
Genode::error("Failed to initialize ssh event file descriptors");
throw -1;
}
_state = SSH_INITIALIZED;
}
@ -596,7 +608,22 @@ void Ssh::Server::loop()
{
Util::Pthread_mutex::Guard guard(_terminals.mutex());
/* first remove all stale sessions */
/* finish pending initialization of terminal sessions */
auto initialize = [&] (Terminal_session &t) {
try {
if (t._state == Terminal_session::PIPE_INITIALIZED) {
t.initialize_ssh_event_fds();
}
} catch (...) {
/* Not sure what to do here - terminal is "almost" attached.
Previously service was denied in that case but as
descriptor handling must be performed in ssh loop thread
it is too late for that. */
}
};
_terminals.for_each(initialize);
/* remove all stale sessions */
auto cleanup = [&] (Session &s) {
if (s.terminal_detached) {
Terminal_session *p = nullptr;

20
repos/gems/src/server/ssh_terminal/server.h
View File

@ -88,16 +88,30 @@ struct Ssh::Terminal_session : Genode::Registry<Terminal_session>::Element
int _fds[2] { -1, -1 };
enum State { UNINITIALIZED,
PIPE_INITIALIZED,
SSH_INITIALIZED } _state = UNINITIALIZED;
Terminal_session(Genode::Registry<Terminal_session> &reg,
Ssh::Terminal &conn,
ssh_event event_loop);
~Terminal_session()
{
ssh_event_remove_fd(_event_loop, _fds[0]);
close(_fds[0]);
close(_fds[1]);
switch (_state) {
case SSH_INITIALIZED:
ssh_event_remove_fd(_event_loop, _fds[0]);
[[fallthrough]];
case PIPE_INITIALIZED:
close(_fds[0]);
close(_fds[1]);
[[fallthrough]];
case UNINITIALIZED:
break;
}
}
void initialize_ssh_event_fds();
};