[PATCH] media: vidtv: fix to initialize local pointers upon transfer of memory ownership

[Jeongjun Park <aha310510@gmail.com>]

vidtv_channel_si_init() transfers ownership of each object to the correct
table through functions such as vidtv_psi_*_assign().

However, since it does not set the local pointer to NULL afterwards, if it
fails for various reasons and jumps to a place such as free_*it, memory
that was freed in vidtv_psi_*_table_destroy() will be accessed and freed
again, resulting in use-after-free and double-free vuln.

Therefore, local pointers that have completed ownership transfer must be
initialized to NULL to prevent re-access to already freed memory.

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>
---
 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);
--