kernel.git/drivers/media/dvb-core/dmxdev.c, branch linux-rolling-stable

media: dvb-core: fix wrong reinitialization of ringbuffer on reopen

2026-03-12T11:09:28Z

commit bfbc0b5b32a8f28ce284add619bf226716a59bc0 upstream. dvb_dvr_open() calls dvb_ringbuffer_init() when a new reader opens the DVR device. dvb_ringbuffer_init() calls init_waitqueue_head(), which reinitializes the waitqueue list head to empty. Since dmxdev->dvr_buffer.queue is a shared waitqueue (all opens of the same DVR device share it), this orphans any existing waitqueue entries from io_uring poll or epoll, leaving them with stale prev/next pointers while the list head is reset to {self, self}. The waitqueue and spinlock in dvr_buffer are already properly initialized once in dvb_dmxdev_init(). The open path only needs to reset the buffer data pointer, size, and read/write positions. Replace the dvb_ringbuffer_init() call in dvb_dvr_open() with direct assignment of data/size and a call to dvb_ringbuffer_reset(), which properly resets pread, pwrite, and error with correct memory ordering without touching the waitqueue or spinlock. Cc: stable@vger.kernel.org Fixes: 34731df288a5f ("V4L/DVB (3501): Dmxdev: use dvb_ringbuffer") Reported-by: syzbot+ab12f0c08dd7ab8d057c@syzkaller.appspotmail.com Tested-by: syzbot+ab12f0c08dd7ab8d057c@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/698a26d3.050a0220.3b3015.007d.GAE@google.com/ Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

media: dvb-core: dmxdevfilter must always flush bufs

2026-03-04T12:19:54Z

[ Upstream commit c4e620eccbef76aa5564ebb295e23d6540e27215 ] Currently the buffers are being filled until full, which works fine for the transport stream, but not when reading sections, those have to be returned to userspace immediately, otherwise dvbv5-scan will just wait forever. Add a 'flush' argument to dvb_vb2_fill_buffer to indicate whether the buffer must be flushed or wait until it is full. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin

media: dvb-core: use vmalloc_array to simplify code

2025-10-14T13:07:36Z

Remove array_size() calls and replace vmalloc() with vmalloc_array() to simplify the code. Signed-off-by: Qianfeng Rong Signed-off-by: Hans Verkuil

treewide, timers: Rename from_timer() to timer_container_of()

2025-06-08T07:07:37Z

Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com

treewide: Switch/rename to timer_delete[_sync]()

2025-04-05T08:30:12Z

timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree over and remove the historical wrapper inlines. Conversion was done with coccinelle plus manual fixups where necessary. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

media: fix secfeed undefined when filter alloc fail

2025-01-08T11:52:36Z

In dvb_dmxdev_filter_start, when secfeed allocate secfilter fail. the secfeed of current dmxfilter, need set to NULL; Instead of call start_filtering, which already handled in dvb_dmxdev_feed_restart Signed-off-by: jieqing.wang Link: https://lore.kernel.org/r/20221201052705.2313911-1-standback@126.com Signed-off-by: Mauro Carvalho Chehab

media: dvb-core: Fix UAF due to refcount races at releasing

2022-11-04T15:56:43Z

The dvb-core tries to sync the releases of opened files at dvb_dmxdev_release() with two refcounts: dvbdev->users and dvr_dvbdev->users. A problem is present in those two syncs: when yet another dvb_demux_open() is called during those sync waits, dvb_demux_open() continues to process even if the device is being closed. This includes the increment of the former refcount, resulting in the leftover refcount after the sync of the latter refcount at dvb_dmxdev_release(). It ends up with use-after-free, since the function believes that all usages were gone and releases the resources. This patch addresses the problem by adding the check of dmxdev->exit flag at dvb_demux_open(), just like dvb_dvr_open() already does. With the exit flag check, the second call of dvb_demux_open() fails, hence the further corruption can be avoided. Also for avoiding the races of the dmxdev->exit flag reference, this patch serializes the dmxdev->exit set up and the sync waits with the dmxdev->mutex lock at dvb_dmxdev_release(). Without the mutex lock, dvb_demux_open() (or dvb_dvr_open()) may run concurrently with dvb_dmxdev_release(), which allows to skip the exit flag check and continue the open process that is being closed. CVE-2022-41218 is assigned to those bugs above. Reported-by: Hyunwoo Kim Cc: Link: https://lore.kernel.org/20220908132754.30532-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Hans Verkuil

media: dvb-core: Convert to SPDX identifier

2021-11-19T15:22:13Z

use SPDX-License-Identifier instead of a verbose license text and remove verbose license text. Link: https://lore.kernel.org/linux-media/20210916020018.8550-1-caihuoqing@baidu.com Signed-off-by: Cai Huoqing Signed-off-by: Mauro Carvalho Chehab

media: dmxdev: fix UAF when dvb_register_device() fails

2021-11-19T15:17:57Z

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@huawei.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Hulk Robot Signed-off-by: Wang Hai Signed-off-by: Mauro Carvalho Chehab

media: dmxdev: change the check for problems allocing secfeed

2021-06-09T12:45:20Z

While the logic there is right, it tricks static check analyzers, like smatch: drivers/media/dvb-core/dmxdev.c:729 dvb_dmxdev_filter_start() error: we previously assumed '*secfeed' could be null (see line 719) Because the implementation of the filter itself is made via a callback, with its real implementation at the dvbdmx_allocate_section_feed() inside dvb_demux.c. So, change the check logic to make it clear that the function will not try to use *secfeed == NULL. Signed-off-by: Mauro Carvalho Chehab