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sd-event: fix fd leak when fd is owned by IO event source

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When an IO event source owns relevant fd, replacing with a new fd leaks
the previously assigned fd.
===
sd_event_add_io(event, &s, fd, ...);
sd_event_source_set_io_fd_own(s, true);
sd_event_source_set_io_fd(s, new_fd);  <-- The previous fd is not closed.
sd_event_source_unref(s);  <-- new_fd is closed as expected.
===

Without the change, valgrind reports the leak:
==998589==
==998589== FILE DESCRIPTORS: 4 open (3 std) at exit.
==998589== Open file descriptor 4:
==998589==    at 0x4F119AB: pipe2 (in /usr/lib64/libc.so.6)
==998589==    by 0x408830: test_sd_event_source_set_io_fd (test-event.c:862)
==998589==    by 0x403302: run_test_table (tests.h:171)
==998589==    by 0x408E31: main (test-event.c:935)
==998589==
==998589==
==998589== HEAP SUMMARY:
==998589==     in use at exit: 0 bytes in 0 blocks
==998589==   total heap usage: 33,305 allocs, 33,305 frees, 1,283,581 bytes allocated
==998589==
==998589== All heap blocks were freed -- no leaks are possible
==998589==
==998589== For lists of detected and suppressed errors, rerun with: -s
==998589== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
This commit is contained in:
Yu Watanabe
2024-04-22 18:30:12 +08:00
committed by Mike Yuan
parent 3ee5e3d046
commit 2fa480592d
3 changed files with 39 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libsystemd/sd-event/sd-event.c
+8 -9
View File
@@ -2647,7 +2647,7 @@ _public_ int sd_event_source_get_io_fd(sd_event_source *s) {
}
_public_ int sd_event_source_set_io_fd(sd_event_source *s, int fd) {
int r;
int saved_fd, r;
assert_return(s, -EINVAL);
assert_return(fd >= 0, -EBADF);
@@ -2657,16 +2657,12 @@ _public_ int sd_event_source_set_io_fd(sd_event_source *s, int fd) {
if (s->io.fd == fd)
return 0;
if (event_source_is_offline(s)) {
s->io.fd = fd;
s->io.registered = false;
} else {
int saved_fd;
saved_fd = s->io.fd;
s->io.fd = fd;
saved_fd = s->io.fd;
assert(s->io.registered);
assert(event_source_is_offline(s) == !s->io.registered);
s->io.fd = fd;
if (s->io.registered) {
s->io.registered = false;
r = source_io_register(s, s->enabled, s->io.events);
@@ -2679,6 +2675,9 @@ _public_ int sd_event_source_set_io_fd(sd_event_source *s, int fd) {
(void) epoll_ctl(s->event->epoll_fd, EPOLL_CTL_DEL, saved_fd, NULL);
}
if (s->io.owned)
safe_close(saved_fd);
return 0;
}
src/libsystemd/sd-event/test-event.c
+18
View File
@@ -843,6 +843,24 @@ TEST(fork) {
assert_se(r >= 0);
}
TEST(sd_event_source_set_io_fd) {
_cleanup_(sd_event_source_unrefp) sd_event_source *s = NULL;
_cleanup_(sd_event_unrefp) sd_event *e = NULL;
_cleanup_close_pair_ int pfd_a[2] = EBADF_PAIR, pfd_b[2] = EBADF_PAIR;
assert_se(sd_event_default(&e) >= 0);
assert_se(pipe2(pfd_a, O_CLOEXEC) >= 0);
assert_se(pipe2(pfd_b, O_CLOEXEC) >= 0);
assert_se(sd_event_add_io(e, &s, pfd_a[0], EPOLLIN, NULL, INT_TO_PTR(-ENOANO)) >= 0);
assert_se(sd_event_source_set_io_fd_own(s, true) >= 0);
TAKE_FD(pfd_a[0]);
assert_se(sd_event_source_set_io_fd(s, pfd_b[0]) >= 0);
TAKE_FD(pfd_b[0]);
}
static int hup_callback(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
unsigned *c = userdata;