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Howlett" , Uladzislau Rezki , Jiri Slaby , "Rafael J. Wysocki" , greybus-dev@lists.linaro.org, linux-serial@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, driver-core@lists.linux.dev Date: Thu, 22 Oct 2026 12:45:37 +0000 In-Reply-To: <2026101758-confidant-comprised-e1c0@gregkh> References: <20261016-rust_serdev_probe_refactor-v4-0-46832e034757@posteo.de> <20261016-rust_serdev_probe_refactor-v4-1-46832e034757@posteo.de> <2026101758-confidant-comprised-e1c0@gregkh> Autocrypt: addr=markus.probst@posteo.de; prefer-encrypt=mutual; keydata=mQINBGiDvXgBEADAXUceKafpl46S35UmDh2wRvvx+UfZbcTjeQOlSwKP7YVJ4JOZrVs93 qReNLkOWguIqPBxR9blQ4nyYrqSCV+MMw/3ifyXIm6Pw2YRUDg+WTEOjTixRCoWDgUj1nOsvJ9tVA m76Ww+/pAnepVRafMID0rqEfD9oGv1YrfpeFJhyE2zUw3SyyNLIKWD6QeLRhKQRbSnsXhGLFBXCqt 9k5JARhgQof9zvztcCVlT5KVvuyfC4H+HzeGmu9201BVyihJwKdcKPq+n/aY5FUVxNTgtI9f8wIbm fAjaoT1pjXSp+dszakA98fhONM98pOq723o/1ZGMZukyXFfsDGtA3BB79HoopHKujLGWAGskzClwT jRQxBqxh/U/lL1pc+0xPWikTNCmtziCOvv0KA0arDOMQlyFvImzX6oGVgE4ksKQYbMZ3Ikw6L1Rv1 J+FvN0aNwOKgL2ztBRYscUGcQvA0Zo1fGCAn/BLEJvQYShWKeKqjyncVGoXFsz2AcuFKe1pwETSsN 6OZncjy32e4ktgs07cWBfx0v62b8md36jau+B6RVnnodaA8++oXl3FRwiEW8XfXWIjy4umIv93tb8 8ekYsfOfWkTSewZYXGoqe4RtK80ulMHb/dh2FZQIFyRdN4HOmB4FYO5sEYFr9YjHLmDkrUgNodJCX CeMe4BO4iaxUQARAQABtCdNYXJrdXMgUHJvYnN0IDxtYXJrdXMucHJvYnN0QHBvc3Rlby5kZT6JAl QEEwEIAD4CGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AWIQSCdBjE9KxY53IwxHM0dh/4561 D0gUCaIZ9HQIZAQAKCRA0dh/4561D0pKmD/92zsCfbD+SrvBpNWtbit7J9wFBNr9qSFFm2n/65qen NNWKDrCzDsjRbALMHSO8nigMWzjofbVjj8Nf7SDcdapRjrMCnidS0DuW3pZBo6W0sZqV/fLx+AzgQ 7PAr6jtBbUoKW/GCGHLLtb6Hv+zjL17KGVO0DdQeoHEXMa48mJh8rS7VlUzVtpbxsWbb1wRZJTD88 ALDOLTWGqMbCTFDKFfGcqBLdUT13vx706Q29wrDiogmQhLGYKc6fQzpHhCLNhHTl8ZVLuKVY3wTT+ f9TzW1BDzFTAe3ZXsKhrzF+ud7vr6ff9p1Zl+Nujz94EDYHi/5Yrtp//+N/ZjDGDmqZOEA86/Gybu 6XE/v4S85ls0cAe37WTqsMCJjVRMP52r7Y1AuOONJDe3sIsDge++XFhwfGPbZwBnwd4gEVcdrKhnO ntuP9TvBMFWeTvtLqlWJUt7n8f/ELCcGoO5acai1iZ59GC81GLl2izObOLNjyv3G6hia/w50Mw9MU dAdZQ2MxM6k+x4L5XeysdcR/2AydVLtu2LGFOrKyEe0M9XmlE6OvziWXvVVwomvTN3LaNUmaINhr7 pHTFwDiZCSWKnwnvD2+jA1trKq1xKUQY1uGW9XgSj98pKyixHWoeEpydr+alSTB43c3m0351/9rYT TTi4KSk73wtapPKtaoIR3rOFHLQXbWFya3VzLnByb2JzdEBwb3N0ZW8uZGWJAlEEEwEIADsWIQSCd BjE9KxY53IwxHM0dh/4561D0gUCaIO9eAIbAwULCQgHAgIiAgYVCgkICwIEFgIDAQIeBwIXgAAKCR A0dh/4561D0oHZEACEmk5Ng9+OXoVxJJ+c9slBI2lYxyBO84qkWjoJ/0GpwoHk1IpyL+i+kF1Bb7y Hx9Tiz8ENYX7xIPTZzS8hXs1ksuo76FQUyD6onA/69xZIrYZ0NSA5HUo62qzzMSZL7od5e12R6OPR lR0PIuc4ecOGCEq3BLRPfZSYrL54tiase8HubXsvb6EBQ8jPI8ZUlr96ZqFEwrQZF/3ihyV6LILLk geExgwlTzo5Wv3piOXPTITBuzuFhBJqEnT25q2j8OumGQ+ri8oVeAzx24g1kc11pwpR0sowfa5MvZ WrrBcaIL7uJfR/ig7FyGnTQ1nS3btf3p0v8A3fc4eUu/K2No3l2huJp3+LHhCmpmeykOhSB63Mj3s 3Q87LD0HE0HBkTEMwp+sD97ZRpO67H5shzJRanUaDTb/mREfzpJmRT1uuec0X2zItL7a6itgMJvYI KG29aJLX3fTzzVzFGPgzVZYEdhu4y53p0qEGrrC1JtKR6DRPE1hb/OdWOkjmJ75+PPLD9U5IuRd6y sHJWsEBR1F0wkMPkEofWsvMYJzWXx/rvTWO8N4D6HigTgBXAXNgbc3IHpHlkvKoBJptv6DRVRtIrz 0G0cfBY0Sm7he4N2IYDWWdGnPBZ3rlLSdj5EiBU2YWgIgtLrb8ZNJ3ZlhYluGnBJDGRqy2jC9s1jY 66sLA9rQZMHhJTzMyIDwweGlvMzJAcG9zdGVvLmV1PokCbQQTAQgAVxYhBIJ0GMT0rFjncjDEczR2 H/jnrUPSBQJpa71VGxSAAAAAAAQADm1hbnUyLDIuNSsxLjExLDIsMgIbAwULCQgHAgIiAgYVCgkIC wIEFgIDAQIeBwIXgAAKCRA0dh/4561D0gKJD/9uOQKYlsDoQX65Gd0LiMT0C+5vXgr3VI0PHDOwcv 51fJ3A1vNyPZRFPGrz8+mDEXUQOF/INfnz5Tu1QHwf+iYcWcTGAN/FHgVR6ET6VBNU2hJaKhu+Ggo kjYyJTOvyX+3yNRUfSny0GjTjIPuPTErjqmHF+BtjXslpgwqnNMznf3lRIuUjRORupos6p3k1DndE 5vzUTmXSvMyXyOD2KhBl/kL76k0bHYyAQytZPag12pltrtFbA/r2phDGN2si8PooDT99bSTJjaM45 MTAAHbHKJfvgfK41bNFD5mMtpWpL195XRtS0Nrxdg3PaYBxN5gtTG0RyZfpYRlkdEhm+jj/8RxuSG i/qdhRdbiI7K2IELWeQVHSNDi9JabR/UzlR4NSnhfAjRIVlRM+eFbUl8XwxwVrAkojF5IraH2qRvg VCmuFsHUW07FUlrDrzpjXsD73cKppoFGDCdDR0BHJepXbFLS9+AqkT+guRJlnCTg2p+TQtnbwPgKp Vj98JixovCl99zRYTsL2bRNU5+q8iET65VMJ1ydyNanvLd5vI/NqDkXhlXLsGmdaDTtu4R21PkToX dQNGrZ91M9nlIBKw8Y7c7xZ4098qX2b8JX/CxD+gC1r4C8vuA3GkhFLx+KlkON7LyiJPkrePp6Qky jfGillcaQOqFZ3WwVqyzG1BUfTow== Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-SSwWWVnFuWrg0GMbs44o" X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt --=-SSwWWVnFuWrg0GMbs44o Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sat, 2026-10-17 at 09:53 +0200, Greg Kroah-Hartman wrote: > On Fri, Oct 16, 2026 at 06:00:32PM +0000, Markus Probst wrote: > > Besides more predictable behaviour, this allows for several hardened > > behaviour changes: > >=20 > > Return -EALREADY in `serdev_device_open` if the device is already open > > instead of causing undefined behaviour. > >=20 > > Allow calling `serdev_device_close`, even if the device is already > > closed instead of causing a null pointer dereference. > >=20 > > If the device is left open by the driver after remove, close it and war= n > > instead of leaving it in a invalid state. > >=20 > > Signed-off-by: Markus Probst > > --- > > drivers/tty/serdev/core.c | 10 +++++--- > > drivers/tty/serdev/serdev-ttyport.c | 46 +++++++++++++++++++++++++++++= ++------ > > include/linux/serdev.h | 2 +- > > 3 files changed, 47 insertions(+), 11 deletions(-) > >=20 > > diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c > > index 7500efcdfc21..77e8e1d4d2a6 100644 > > --- a/drivers/tty/serdev/core.c > > +++ b/drivers/tty/serdev/core.c > > @@ -142,6 +142,11 @@ void serdev_device_remove(struct serdev_device *se= rdev) > > struct serdev_controller *ctrl =3D serdev->ctrl; > > =20 > > device_unregister(&serdev->dev); > > + > > + /* Warn if driver did not close the serial device. */ > > + if (ctrl->ops->close && WARN_ON(ctrl->ops->close(ctrl))) >=20 > I understand the want to give a big "splat" if this happens, but if it > does somehow, you just crashed the box due to panic-on-warn, which will > result in a CVE being given :) >=20 > So, if this ever can happen, we should recover like you do: >=20 > > + pm_runtime_put(&ctrl->dev); >=20 > And you can warn about it in the kernel log, but just not with WARN_ON() > please. To be honest, I forgot about this review and sent v5 without taking it into account. Anyway, I looked into documentation. "WARN*() is intended for unexpected, this-should-never-happen situations. [...] However, the existence of panic_on_warn users is not a valid reason to avoid the judicious use WARN*()." [1] I think this is a valid case. It is an event that should never happen, and it might cause a use- after-free vulnerability on data reception. Thanks - Markus Probst [1] https://docs.kernel.org/process/coding-style.html >=20 > thanks, >=20 > greg k-h --=-SSwWWVnFuWrg0GMbs44o Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQJPBAABCAA5FiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IFAmraBW4bFIAAAAAABAAO bWFudTIsMi41KzEuMTIsMiwyAAoJEDR2H/jnrUPSwncP/iqL6bpaPmb2KVjSz1X8 p358eOolNLI70BYGrtESeG/h0huOgPn5p8TuhIP5tBKy5n69GkmlbEiF5yKhc8YE 2GRpyGQ+w8ZjlWrM40hxB+HHTrlduJmUJDSJJgm7c18H/hsqkslQz4348XpyBAjj Lg0OBumSzX7CMqwRlfbxzFC3ec/owCuavuNfj246WBij1yUlR7TPAsZOoovEvx27 aWN+tiQQODux5Fzgi9c2l+FHVJTipUJms1HS1z2Vs4oY6TN85fazkxUHqdvYoj/4 19+cmqeBcyrNqVk03YKDieYfR55eMpJsOuW+b+Y7aIBhhqJDVwQsCSGjGOBtFJGe nycaPLRb1Ex46Lm/1Fydpk042CcLuDwY5AqbP2N6f33cNtIZjmlTDLAG5nXZbqDh ulff8KixN4ODX65YGTWVdaT9SvM7UA49fq/Zt9o8ZU6HSHzZF5eWl1CV5yf9Lqm6 QfbUdNFoClwH6ctJ2w/gU+uwaYvWPLpc5ynUJZA56Y7RpkyMfbn00qLnhf35RkzF S7swLkYBcKB9oIe4RjSaJdXkvEDjbGPNXb2Q/kMdq9qM14ZYFtXzJEOU9v8ZYlsz NL/GpKAhFFPlpyXuT7z41ae27X06Vjl5VWhjK9Nn/F/Q+VgHQT/rSrXeJVkz6HPF W0Zp6OLY3R0kDvrRE457NGNW =LcdA -----END PGP SIGNATURE----- --=-SSwWWVnFuWrg0GMbs44o--