Date: Wed, 22 Jul 2026 15:12:50 +0000 From: Baptiste Daroussin <bapt@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 12b4a02bd881 - main - uvideo: fix close/detach race on streaming teardown Message-ID: <6a60ddf2.33f9c.710b3d4a@gitrepo.freebsd.org>
index | next in thread | raw e-mail
The branch main has been updated by bapt: URL: https://cgit.FreeBSD.org/src/commit/?id=12b4a02bd88117b07f3e142af71b70bade4fd57e commit 12b4a02bd88117b07f3e142af71b70bade4fd57e Author: Baptiste Daroussin <bapt@FreeBSD.org> AuthorDate: 2026-07-22 08:18:23 +0000 Commit: Baptiste Daroussin <bapt@FreeBSD.org> CommitDate: 2026-07-22 15:10:58 +0000 uvideo: fix close/detach race on streaming teardown detach() stopped streaming and called uvideo_vs_close() before destroy_dev(), so a concurrent close() could race the teardown and call uvideo_vs_close() a second time (double usbd_transfer_unsetup), and mtx_destroy() could race a close still holding sc_mtx. sc_streaming was also read without the lock in both paths. Reorder detach() to call destroy_dev() first so all in-flight cdev methods drain before any teardown. Read sc_streaming under sc_mtx in both detach() and the last-close safety net. --- sys/dev/usb/video/uvideo.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/sys/dev/usb/video/uvideo.c b/sys/dev/usb/video/uvideo.c index bfcd6696a8e0..57d31d2b5286 100644 --- a/sys/dev/usb/video/uvideo.c +++ b/sys/dev/usb/video/uvideo.c @@ -960,21 +960,20 @@ uvideo_detach(device_t dev) sc->sc_dying = 1; - /* Stop any active streaming */ - if (sc->sc_streaming) { - mtx_lock(&sc->sc_mtx); - sc->sc_streaming = 0; - mtx_unlock(&sc->sc_mtx); - uvideo_vs_close(sc); - } - /* Destroy character device */ if (sc->sc_cdev != NULL) { destroy_dev(sc->sc_cdev); sc->sc_cdev = NULL; } - /* Unit number is implicitly freed when the cdev is destroyed */ + /* Stop streaming if still active (e.g. detached while idle). */ + mtx_lock(&sc->sc_mtx); + if (sc->sc_streaming) { + sc->sc_streaming = 0; + mtx_unlock(&sc->sc_mtx); + uvideo_vs_close(sc); + } else + mtx_unlock(&sc->sc_mtx); /* Free frame buffers */ uvideo_vs_free_frame(sc); @@ -2911,12 +2910,13 @@ uvideo_cdev_close(struct cdev *dev, int flags, int fmt, struct thread *td) mtx_unlock(&sc->sc_mtx); /* Last close: stop streaming if still active (safety net) */ + mtx_lock(&sc->sc_mtx); if (sc->sc_streaming) { - mtx_lock(&sc->sc_mtx); sc->sc_streaming = 0; mtx_unlock(&sc->sc_mtx); uvideo_vs_close(sc); - } + } else + mtx_unlock(&sc->sc_mtx); uvideo_vs_free_frame(sc);home | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?6a60ddf2.33f9c.710b3d4a>