From: Wang Hai <wanghai38@xxxxxxxxxx> [ Upstream commit ab599eb11882f834951c436cc080c3455ba32b9b ] I got a use-after-free report: dvbdev: dvb_register_device: failed to create device dvb1.dvr0 (-12) ... ================================================================== BUG: KASAN: use-after-free in dvb_dmxdev_release+0xce/0x2f0 ... Call Trace: dump_stack_lvl+0x6c/0x8b print_address_description.constprop.0+0x48/0x70 kasan_report.cold+0x82/0xdb __asan_load4+0x6b/0x90 dvb_dmxdev_release+0xce/0x2f0 ... Allocated by task 7666: kasan_save_stack+0x23/0x50 __kasan_kmalloc+0x83/0xa0 kmem_cache_alloc_trace+0x22e/0x470 dvb_register_device+0x12f/0x980 dvb_dmxdev_init+0x1f3/0x230 ... Freed by task 7666: kasan_save_stack+0x23/0x50 kasan_set_track+0x20/0x30 kasan_set_free_info+0x24/0x40 __kasan_slab_free+0xf2/0x130 kfree+0xd1/0x5c0 dvb_register_device.cold+0x1ac/0x1fa dvb_dmxdev_init+0x1f3/0x230 ... When dvb_register_device() in dvb_dmxdev_init() fails, dvb_dmxdev_init() does not return a failure, and the memory pointed to by dvbdev or dvr_dvbdev is invalid at this point. If they are used subsequently, it will result in UFA or null-ptr-deref. If dvb_register_device() in dvb_dmxdev_init() fails, fix the bug by making dvb_dmxdev_init() return an error as well. Link: https://lore.kernel.org/linux-media/20211015085741.1203283-1-wanghai38@xxxxxxxxxx Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Hulk Robot <hulkci@xxxxxxxxxx> Signed-off-by: Wang Hai <wanghai38@xxxxxxxxxx> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/media/dvb-core/dmxdev.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/media/dvb-core/dmxdev.c b/drivers/media/dvb-core/dmxdev.c index 5d5a48475a54f..01f288fa37e0e 100644 --- a/drivers/media/dvb-core/dmxdev.c +++ b/drivers/media/dvb-core/dmxdev.c @@ -1413,7 +1413,7 @@ static const struct dvb_device dvbdev_dvr = { }; int dvb_dmxdev_init(struct dmxdev *dmxdev, struct dvb_adapter *dvb_adapter) { - int i; + int i, ret; if (dmxdev->demux->open(dmxdev->demux) < 0) return -EUSERS; @@ -1432,14 +1432,26 @@ int dvb_dmxdev_init(struct dmxdev *dmxdev, struct dvb_adapter *dvb_adapter) DMXDEV_STATE_FREE); } - dvb_register_device(dvb_adapter, &dmxdev->dvbdev, &dvbdev_demux, dmxdev, + ret = dvb_register_device(dvb_adapter, &dmxdev->dvbdev, &dvbdev_demux, dmxdev, DVB_DEVICE_DEMUX, dmxdev->filternum); - dvb_register_device(dvb_adapter, &dmxdev->dvr_dvbdev, &dvbdev_dvr, + if (ret < 0) + goto err_register_dvbdev; + + ret = dvb_register_device(dvb_adapter, &dmxdev->dvr_dvbdev, &dvbdev_dvr, dmxdev, DVB_DEVICE_DVR, dmxdev->filternum); + if (ret < 0) + goto err_register_dvr_dvbdev; dvb_ringbuffer_init(&dmxdev->dvr_buffer, NULL, 8192); return 0; + +err_register_dvr_dvbdev: + dvb_unregister_device(dmxdev->dvbdev); +err_register_dvbdev: + vfree(dmxdev->filter); + dmxdev->filter = NULL; + return ret; } EXPORT_SYMBOL(dvb_dmxdev_init); -- 2.34.1
