Date: Sun, 28 Apr 2024 19:48:59 GMT From: Christos Margiolis <christos@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 074d6fbebc16 - main - sound: Fix NULL dereference in dsp_clone() and mixer_clone() Message-ID: <202404281948.43SJmxt6063120@gitrepo.freebsd.org>
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The branch main has been updated by christos: URL: https://cgit.FreeBSD.org/src/commit/?id=074d6fbebc160222cde6b726adcc7350881d7824 commit 074d6fbebc160222cde6b726adcc7350881d7824 Author: Christos Margiolis <christos@FreeBSD.org> AuthorDate: 2024-04-28 19:40:14 +0000 Commit: Christos Margiolis <christos@FreeBSD.org> CommitDate: 2024-04-28 19:48:24 +0000 sound: Fix NULL dereference in dsp_clone() and mixer_clone() If we only have a single soundcard attached and we detach it right before entering [dsp|mixer]_clone(), there is a chance pcm_unregister() will have returned already, meaning it will have set snd_unit to -1, and thus devclass_get_softc() will return NULL here. While here, 1) move the calls to dsp_destroy_dev() and mixer_uninit() below the point where we unset SD_F_REGISTERED, and 2) follow what mixer_clone() does and make sure we don't use a NULL d->dsp_dev in dsp_clone(). Reported by: KASAN Sponsored by: The FreeBSD Foundation MFC after: 1 day Reviewed by: markj Differential Revision: https://reviews.freebsd.org/D44924 --- sys/dev/sound/pcm/dsp.c | 14 ++++++++++---- sys/dev/sound/pcm/mixer.c | 3 ++- sys/dev/sound/pcm/sound.c | 7 +++---- 3 files changed, 15 insertions(+), 9 deletions(-) diff --git a/sys/dev/sound/pcm/dsp.c b/sys/dev/sound/pcm/dsp.c index 1c020ba22611..c5bb27530d2b 100644 --- a/sys/dev/sound/pcm/dsp.c +++ b/sys/dev/sound/pcm/dsp.c @@ -2086,10 +2086,16 @@ dsp_clone(void *arg, struct ucred *cred, char *name, int namelen, return; found: d = devclass_get_softc(pcm_devclass, snd_unit); - if (!PCM_REGISTERED(d)) - return; - *dev = d->dsp_dev; - dev_ref(*dev); + /* + * If we only have a single soundcard attached and we detach it right + * before entering dsp_clone(), there is a chance pcm_unregister() will + * have returned already, meaning it will have set snd_unit to -1, and + * thus devclass_get_softc() will return NULL here. + */ + if (d != NULL && PCM_REGISTERED(d) && d->dsp_dev != NULL) { + *dev = d->dsp_dev; + dev_ref(*dev); + } } static void diff --git a/sys/dev/sound/pcm/mixer.c b/sys/dev/sound/pcm/mixer.c index 0178e1ae8c3e..33a7eb26606d 100644 --- a/sys/dev/sound/pcm/mixer.c +++ b/sys/dev/sound/pcm/mixer.c @@ -1378,7 +1378,8 @@ mixer_clone(void *arg, return; if (strcmp(name, "mixer") == 0) { d = devclass_get_softc(pcm_devclass, snd_unit); - if (PCM_REGISTERED(d) && d->mixer_dev != NULL) { + /* See related comment in dsp_clone(). */ + if (d != NULL && PCM_REGISTERED(d) && d->mixer_dev != NULL) { *dev = d->mixer_dev; dev_ref(*dev); } diff --git a/sys/dev/sound/pcm/sound.c b/sys/dev/sound/pcm/sound.c index e88ccb1f25a6..faf4bd1c7dce 100644 --- a/sys/dev/sound/pcm/sound.c +++ b/sys/dev/sound/pcm/sound.c @@ -1013,10 +1013,6 @@ pcm_unregister(device_t dev) CHN_UNLOCK(ch); } - dsp_destroy_dev(dev); - - (void)mixer_uninit(dev); - /* remove /dev/sndstat entry first */ sndstat_unregister(dev); @@ -1034,6 +1030,9 @@ pcm_unregister(device_t dev) d->rec_sysctl_tree = NULL; } + dsp_destroy_dev(dev); + (void)mixer_uninit(dev); + while (!CHN_EMPTY(d, channels.pcm)) pcm_killchan(dev);
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