git: 9ac0aec3a32c - stable/13 - lio_listio: Don't post a completion notification if none was requested

[Mark Johnston]

The branch stable/13 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=9ac0aec3a32c84599cfbcc9f70ca2e035a3ddc0b

commit 9ac0aec3a32c84599cfbcc9f70ca2e035a3ddc0b
Author:     Mark Johnston <markj at FreeBSD.org>
AuthorDate: 2021-07-16 02:38:46 +0000
Commit:     Mark Johnston <markj at FreeBSD.org>
CommitDate: 2021-07-30 00:32:58 +0000

    lio_listio: Don't post a completion notification if none was requested
    
    One is allowed to use LIO_NOWAIT without specifying a sigevent.  In this
    case, lj->lioj_signal is left uninitialized, but several code paths
    examine liov_signal.sigev_notify to figure out which notification to
    post.  Unconditionally initialize that field to SIGEV_NONE.
    
    Add a dumb test case which triggers the bug.
    
    Reported by:    KMSAN+syzkaller
    Reviewed by:    asomers
    Sponsored by:   The FreeBSD Foundation
    
    (cherry picked from commit 2e5f6152952e4cfbaab3d96368c3dc4218786632)
---
 sys/kern/vfs_aio.c       |  1 +
 tests/sys/aio/lio_test.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/sys/kern/vfs_aio.c b/sys/kern/vfs_aio.c
index 640e82b6f0ff..7d4d9ac3e94b 100644
--- a/sys/kern/vfs_aio.c
+++ b/sys/kern/vfs_aio.c
@@ -2246,6 +2246,7 @@ kern_lio_listio(struct thread *td, int mode, struct aiocb * const *uacb_list,
 	lj->lioj_flags = 0;
 	lj->lioj_count = 0;
 	lj->lioj_finished_count = 0;
+	lj->lioj_signal.sigev_notify = SIGEV_NONE;
 	knlist_init_mtx(&lj->klist, AIO_MTX(ki));
 	ksiginfo_init(&lj->lioj_ksi);
 
diff --git a/tests/sys/aio/lio_test.c b/tests/sys/aio/lio_test.c
index fb519aac978d..a4f5a6a38632 100644
--- a/tests/sys/aio/lio_test.c
+++ b/tests/sys/aio/lio_test.c
@@ -133,6 +133,15 @@ ATF_TC_BODY(lio_listio_empty_wait, tc)
 	ATF_REQUIRE_EQ(0, lio_listio(LIO_WAIT, &list, 0, NULL));
 }
 
+/* With LIO_NOWAIT, an empty lio_listio should return immediately */
+ATF_TC_WITHOUT_HEAD(lio_listio_empty_nowait);
+ATF_TC_BODY(lio_listio_empty_nowait, tc)
+{
+	struct aiocb *list = NULL;
+
+	ATF_REQUIRE_EQ(0, lio_listio(LIO_NOWAIT, &list, 0, NULL));
+}
+
 /*
  * With LIO_NOWAIT, an empty lio_listio should send completion notification
  * immediately
@@ -253,6 +262,7 @@ ATF_TP_ADD_TCS(tp)
 {
 
 	ATF_TP_ADD_TC(tp, lio_listio_eagain_kevent);
+	ATF_TP_ADD_TC(tp, lio_listio_empty_nowait);
 	ATF_TP_ADD_TC(tp, lio_listio_empty_nowait_kevent);
 	ATF_TP_ADD_TC(tp, lio_listio_empty_nowait_signal);
 	ATF_TP_ADD_TC(tp, lio_listio_empty_nowait_thread);