vidtv_channel_si_init() creates a temporary list (program, service, event) and ownership of the memory itself is transferred to the PAT/SDT/EIT tables through vidtv_psi_pat_program_assign(), vidtv_psi_sdt_service_assign(), vidtv_psi_eit_event_assign().
The problem here is that the local pointer where the memory ownership transfer was completed is not initialized to NULL. This causes the vidtv_psi_pmt_create_sec_for_each_pat_entry() function to fail, and in the flow that jumps to free_eit, the memory that was freed by vidtv_psi_*_table_destroy() can be accessed again by vidtv_psi_*_event_destroy() due to the uninitialized local pointer, so it is freed once again.
Therefore, to prevent use-after-free and double-free vulnerability, local pointers must be initialized to NULL when transferring memory ownership.
Cc: stable@vger.kernel.org Reported-by: syzbot+1d9c0edea5907af239e0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1d9c0edea5907af239e0 Fixes: 3be8037960bc ("media: vidtv: add error checks") Signed-off-by: Jeongjun Park aha310510@gmail.com --- v3: Improved patch description wording - Link to v2: https://lore.kernel.org/all/20250904054000.3848107-1-aha310510@gmail.com/ v2: Improved patch description wording and CC stable mailing list - Link to v1: https://lore.kernel.org/all/20250822065849.1145572-1-aha310510@gmail.com/ --- drivers/media/test-drivers/vidtv/vidtv_channel.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/media/test-drivers/vidtv/vidtv_channel.c b/drivers/media/test-drivers/vidtv/vidtv_channel.c index f3023e91b3eb..3541155c6fc6 100644 --- a/drivers/media/test-drivers/vidtv/vidtv_channel.c +++ b/drivers/media/test-drivers/vidtv/vidtv_channel.c @@ -461,12 +461,15 @@ int vidtv_channel_si_init(struct vidtv_mux *m)
/* assemble all programs and assign to PAT */ vidtv_psi_pat_program_assign(m->si.pat, programs); + programs = NULL;
/* assemble all services and assign to SDT */ vidtv_psi_sdt_service_assign(m->si.sdt, services); + services = NULL;
/* assemble all events and assign to EIT */ vidtv_psi_eit_event_assign(m->si.eit, events); + events = NULL;
m->si.pmt_secs = vidtv_psi_pmt_create_sec_for_each_pat_entry(m->si.pat, m->pcr_pid); --