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lio_listio: Don't post a completion notification if none was requested

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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
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D31197
This commit is contained in:
Mark Johnston 2021-07-15 22:38:46 -04:00
parent 9c97062b62
commit 2e5f615295
2 changed files with 11 additions and 0 deletions
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1
sys/kern/vfs_aio.c
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@ -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);

10
tests/sys/aio/lio_test.c
View File

@ -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);