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media: vidtv: initialize local pointers upon transfer of memory ownership

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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: 3be8037960 ("media: vidtv: add error checks")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Jeongjun Park
2025-09-05 14:18:16 +09:00
committed by Hans Verkuil
parent be440980ea
commit 98aabfe2d7
1 changed files with 3 additions and 0 deletions
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3
drivers/media/test-drivers/vidtv/vidtv_channel.c
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@@ -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);