* Re: [PATCH] media: vidtv: fix mutex use-after-destroy in vidtv_bridge_remove() [not found] <20260830075523.16233-1-kartikey406@gmail.com> @ 2026-08-30 7:55 ` syzbot 0 siblings, 0 replies; 2+ messages in thread From: syzbot @ 2026-08-30 7:55 UTC (permalink / raw) To: kartikey406; +Cc: kartikey406, linux-kernel, syzkaller-bugs > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master This crash does not have a reproducer. I cannot test it. > > > mutex_destroy(&dvb->feed_lock) is called too early in > vidtv_bridge_remove(), before dvb_dmxdev_release() and > dvb_dmx_release(). Both of these can still trigger vidtv_stop_feed(), > which locks feed_lock, causing DEBUG_LOCKS_WARN_ON(lock->magic != > lock) in __mutex_lock(). > > Fix by moving mutex_destroy() to after dvb_dmxdev_release() and > dvb_dmx_release() return, and by stopping any active streaming under > feed_lock beforehand so a late vidtv_stop_feed() call sees > dvb->streaming == false and returns early. > > Reported-by: syzbot+3157015c6bd85395cddc@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=3157015c6bd85395cddc > Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com> > --- > drivers/media/test-drivers/vidtv/vidtv_bridge.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c b/drivers/media/test-drivers/vidtv/vidtv_bridge.c > index fd69b4ee16f4..6bebf4617100 100644 > --- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c > +++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c > @@ -548,7 +548,14 @@ static void vidtv_bridge_remove(struct platform_device *pdev) > media_device_cleanup(&dvb->mdev); > #endif /* CONFIG_MEDIA_CONTROLLER_DVB */ > > - mutex_destroy(&dvb->feed_lock); > + mutex_lock(&dvb->feed_lock); > + if (dvb->streaming) { > + dvb->streaming = false; > + vidtv_mux_stop_thread(dvb->mux); > + vidtv_mux_destroy(dvb->mux); > + dvb->mux = NULL; > + } > + mutex_unlock(&dvb->feed_lock); > > for (i = 0; i < NUM_FE; ++i) { > dvb_unregister_frontend(dvb->fe[i]); > @@ -559,6 +566,9 @@ static void vidtv_bridge_remove(struct platform_device *pdev) > dvb_dmxdev_release(&dvb->dmx_dev); > dvb_dmx_release(&dvb->demux); > dvb_unregister_adapter(&dvb->adapter); > + > + mutex_destroy(&dvb->feed_lock); > + > dev_info(&pdev->dev, "Successfully removed vidtv\n"); > } > > -- > 2.43.0 > ^ permalink raw reply [flat|nested] 2+ messages in thread
[parent not found: <20260830075708.16258-1-kartikey406@gmail.com>]
* Re: [PATCH] media: vidtv: fix mutex use-after-destroy in vidtv_bridge_remove() [not found] <20260830075708.16258-1-kartikey406@gmail.com> @ 2026-08-30 7:57 ` syzbot 0 siblings, 0 replies; 2+ messages in thread From: syzbot @ 2026-08-30 7:57 UTC (permalink / raw) To: kartikey406; +Cc: kartikey406, linux-kernel, syzkaller-bugs > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master This crash does not have a reproducer. I cannot test it. > > > mutex_destroy(&dvb->feed_lock) is called too early in > vidtv_bridge_remove(), before dvb_dmxdev_release() and > dvb_dmx_release(). Both of these can still trigger vidtv_stop_feed(), > which locks feed_lock, causing DEBUG_LOCKS_WARN_ON(lock->magic != > lock) in __mutex_lock(). > > Fix by moving mutex_destroy() to after dvb_dmxdev_release() and > dvb_dmx_release() return, and by stopping any active streaming under > feed_lock beforehand so a late vidtv_stop_feed() call sees > dvb->streaming == false and returns early. > > Reported-by: syzbot+3157015c6bd85395cddc@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=3157015c6bd85395cddc > Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com> > --- > drivers/media/test-drivers/vidtv/vidtv_bridge.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c b/drivers/media/test-drivers/vidtv/vidtv_bridge.c > index fd69b4ee16f4..6bebf4617100 100644 > --- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c > +++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c > @@ -548,7 +548,14 @@ static void vidtv_bridge_remove(struct platform_device *pdev) > media_device_cleanup(&dvb->mdev); > #endif /* CONFIG_MEDIA_CONTROLLER_DVB */ > > - mutex_destroy(&dvb->feed_lock); > + mutex_lock(&dvb->feed_lock); > + if (dvb->streaming) { > + dvb->streaming = false; > + vidtv_mux_stop_thread(dvb->mux); > + vidtv_mux_destroy(dvb->mux); > + dvb->mux = NULL; > + } > + mutex_unlock(&dvb->feed_lock); > > for (i = 0; i < NUM_FE; ++i) { > dvb_unregister_frontend(dvb->fe[i]); > @@ -559,6 +566,9 @@ static void vidtv_bridge_remove(struct platform_device *pdev) > dvb_dmxdev_release(&dvb->dmx_dev); > dvb_dmx_release(&dvb->demux); > dvb_unregister_adapter(&dvb->adapter); > + > + mutex_destroy(&dvb->feed_lock); > + > dev_info(&pdev->dev, "Successfully removed vidtv\n"); > } > > -- > 2.43.0 > ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2026-08-30 7:57 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
[not found] <20260830075523.16233-1-kartikey406@gmail.com>
2026-08-30 7:55 ` [PATCH] media: vidtv: fix mutex use-after-destroy in vidtv_bridge_remove() syzbot
[not found] <20260830075708.16258-1-kartikey406@gmail.com>
2026-08-30 7:57 ` syzbot
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.