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Fri, 20 Feb 2026 06:58:14 -0800 (PST) From: Abd-Alrhman Masalkhi To: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= , Ding Yihan Cc: dwlsalmeida@gmail.com, mchehab@kernel.org, linmag7@gmail.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+96f901260a0b2d29cd1a@syzkaller.appspotmail.com Subject: Re: [PATCH] media: vidtv: fix uninitialized args.buf_sz passed by value In-Reply-To: <20260220145236-d4661904-0ed8-4c04-8bdd-09f537b70ba4@linutronix.de> References: <20260220145236-d4661904-0ed8-4c04-8bdd-09f537b70ba4@linutronix.de> Date: Fri, 20 Feb 2026 15:58:13 +0100 Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Fri, Feb 20, 2026 at 14:56 +0100, Thomas Wei=C3=9Fschuh wrote: > Hi Yihan Ding, > > On Fri, Feb 20, 2026 at 09:39:45PM +0800, Ding Yihan wrote: >> While looking into this exact same syzbot report, I noticed that=20 >> `vidtv_ts_pcr_write_into()` in the same file also suffers from the >> exact same pass-by-value anti-pattern (passing `struct pcr_write_args` = by value).=20 > > Good catch. >=20=20 >> Since `pcr_write_args` also contains implicit padding, it remains a pote= ntial trigger >> for identical KMSAN uninit-value warnings during fuzzing in the future. > > The fact that the report is about implicit padding is valuable informatio= n. > It should be part of the commit message. > >> Also, regarding Thomas's concern about modifying shared data: passing th= e struct=20 >> as a `const pointer` (e.g., `const struct null_packet_write_args *`)=20 >> would perfectly guarantee that the state remains read-only. > > Agreed. > >> Thomas, would it be worth submitting a separate patch now to fix >> `vidtv_ts_pcr_write_into()` to prevent future KMSAN errors? Or would you >> prefer this to be addressed together in Abd-Alrhman's v2? > > Doing it together sounds better. This is not urgent anyways in my opinion. > But on the other hand I am just a random guy whose commit got wrongly bla= med > in the original Fixes tag and I don't know anything about this subsystem. > Sorry, I have misunderstood how the 'Fixes' tag works. > > Thomas --=20 Best Regards, Abd-Alrhman