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([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2466877c732sm20969715ad.1.2025.08.23.04.57.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 23 Aug 2025 04:57:31 -0700 (PDT) From: Jeongjun Park To: dwlsalmeida@gmail.com, mchehab@kernel.org Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+1d9c0edea5907af239e0@syzkaller.appspotmail.com, Jeongjun Park Subject: [PATCH v2] media: vidtv: initialize local pointers upon transfer of memory ownership Date: Sat, 23 Aug 2025 20:56:59 +0900 Message-Id: <20250823115659.1176464-1-aha310510@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 vuln, local pointers must be initialized to NULL when transferring memory ownership. Cc: Reported-by: syzbot+1d9c0edea5907af239e0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D1d9c0edea5907af239e0 Fixes: 3be8037960bc ("media: vidtv: add error checks") Signed-off-by: Jeongjun Park --- v2: Improved patch description wording and CC stable mailing list - Link to v1: https://lore.kernel.org/all/20250822065849.1145572-1-aha31051= 0@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/med= ia/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) =20 /* assemble all programs and assign to PAT */ vidtv_psi_pat_program_assign(m->si.pat, programs); + programs =3D NULL; =20 /* assemble all services and assign to SDT */ vidtv_psi_sdt_service_assign(m->si.sdt, services); + services =3D NULL; =20 /* assemble all events and assign to EIT */ vidtv_psi_eit_event_assign(m->si.eit, events); + events =3D NULL; =20 m->si.pmt_secs =3D vidtv_psi_pmt_create_sec_for_each_pat_entry(m->si.pat, m->pcr_pid); --