From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout02.posteo.de (mout02.posteo.de [185.67.36.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD1C13793A9 for ; Sat, 5 Sep 2026 13:30:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788615029; cv=none; b=SkIOUtHPQ9h833ZrdPI9934ekVA1mVBq//dit943LyQeMW4N9+mD+oncP3JzCYzkvS3nf1XpuVfw+V17kcFOrevCWtw1R3TS8LajAX0TgL6sXO5SVFGU+O3+H4NsoHJLnaKzl8GEtdjpqd2HX47jhmlR2sxPFNST0yYDI4esVKI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788615029; c=relaxed/simple; bh=BZQUtMHrD+me98+Sj/eBVIJBH6xrBlHO3wfkHw8pxXg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=a9cI4XnaxSm+n6baMc5354hZrbRfp4ZFp5orNBsfUevhRV3CGuIpkuxWHTQ6Jm+1czKVy3HYs50sFAt8mxhoawf8enL4m4f+EEYbx/VgD/Wm2bykHsartAlHWWYt2c4cERg/SVgbHMvForPW8mMuh37c+Dlsz7VVnfymevoRT+Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de; spf=pass smtp.mailfrom=posteo.de; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b=QiUshLNJ; arc=none smtp.client-ip=185.67.36.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=posteo.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b="QiUshLNJ" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id 0BE71240101 for ; Sat, 5 Sep 2026 15:30:12 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=1984.8680eb; t=1788615012; bh=MrDkKb4gk1/O+1BEUuWrVty7ZyLmE9+t9jPdH84ytmw=; h=From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:To:Cc:Autocrypt:OpenPGP:From; b=QiUshLNJs8RYDPLI+Aa4TqLMk7YS0hzUiyeQE4cET39XEPW1FSWNTMGy94fctnOal HOBTAd3mqLuQaXbSI7ucbYvNToncz+ekELnCSoTEVknEAGS4YwcyVjYF0JadnwmI6m XftSgrtpkVsmcdSyPPgyeUr8d/tdkQ6c6nRqkqS9eL1GG9KR0y6/6Z71gqwYii5GLE 1FBvQau+VNOmQH1t9mySynd6iqiVzXzAf3ba+itJOLgxfkyizFYNPvZWwxGmyItS3X Aj1TAytyhvzLmYjtN9H6SE3PmzUZIaSPtR04M3D3fE/DYv2LlEtYzVv7s4HNfaWQPn vZ4UmSN9Kpd+g== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4hcZ2T55DMz9rxN; Sat, 5 Sep 2026 15:30:09 +0200 (CEST) From: Markus Probst Date: Sat, 05 Sep 2026 13:30:10 +0000 Subject: [PATCH v2 1/2] rust: serdev: Fix race condition on driver unbind 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: 7bit Message-Id: <20260905-rust_serdev_fix-v2-1-35dfcd06ef2e@posteo.de> References: <20260905-rust_serdev_fix-v2-0-35dfcd06ef2e@posteo.de> In-Reply-To: <20260905-rust_serdev_fix-v2-0-35dfcd06ef2e@posteo.de> To: Miguel Ojeda , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?utf-8?q?Onur_=C3=96zkan?= , Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: linux-serial@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, Markus Probst , Sashiko Bot X-Developer-Signature: v=1; a=openpgp-sha256; l=3695; i=markus.probst@posteo.de; h=from:subject:message-id; bh=BZQUtMHrD+me98+Sj/eBVIJBH6xrBlHO3wfkHw8pxXg=; b=owEBiQJ2/ZANAwAIATR2H/jnrUPSAcsmYgBqnBlfwrgbxrP39RWc0Un3ocC38mN8MvT3bVFn1 rXK3vAGKJGJAk8EAAEIADkWIQSCdBjE9KxY53IwxHM0dh/4561D0gUCapwZXxsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQNHYf+OetQ9JY/g/9HYQlJiyM2DHtMe8umM9Qvu710zYhew9 AkLL4wgfJ0qK5rb9cvcvyAxOdE0KnTsjRYuC+zC94IvVnTAK8s9X/Y1v4cvG7w1ETC3dRZoqEBX UJenMuj1LAN+kIYpWM7+orq8ZxlYAUEtWFqtH1ANy8wSbI5VS0Ove4YSSdVk8BfPkjQJgXmT4KT hodcJ2ZSxvy+vrUvwMQ6gJgy1mT00FslDZc9HzEMQSGvyzgTQj87i8U5ymRVEc8GRATK3ySipKN jUHemxLa7qz892q9YKraHAdXbg4Metda1znwzsYHw6jO+LNgDzZhX98A8xzNT8f6jtJ/nvkxoWu EuklbtEiCpHf9YgHlalryLs7dxldLZx0uHDBnJ/yEYyGHs7JkPlLAwnaECndfwsq4PhlrUjkhIs iJ6NYpkl/mYpZk6peFKT8wuGbRg+tGYlHlc+eMAhLbvqo05LBE1bHK/uaOoioIlj0KidYjveajb p80uh8KaGRsgJnse+DKwsLhxZmH2d6Ifxux9iyw8UFowZhWUQTtw2rUSuwM9Kz9LP3KnrIAzIli XWhFzKptfHKiYOncXzqx/5965Rf24FZZaZ+9/rMcEjt9pj0BAa0JYDKbRTuRzaW0Jed7pPfSSZv 2+6a0sTZ1hdXmoyCVAdlzPtWfYbBuLVJdarCm6b4T3rTCn6BBx8k= X-Developer-Key: i=markus.probst@posteo.de; a=openpgp; fpr=827418C4F4AC58E77230C47334761FF8E7AD43D2 Autocrypt: addr=markus.probst@posteo.de; prefer-encrypt=mutual; keydata=xsFNBGiDvXgBEADAXUceKafpl46S35UmDh2wRvvx+UfZbcTjeQOlSwKP7YVJ4JOZrVs93qReNLkO WguIqPBxR9blQ4nyYrqSCV+MMw/3ifyXIm6Pw2YRUDg+WTEOjTixRCoWDgUj1nOsvJ9tVAm76Ww+ /pAnepVRafMID0rqEfD9oGv1YrfpeFJhyE2zUw3SyyNLIKWD6QeLRhKQRbSnsXhGLFBXCqt9k5JA RhgQof9zvztcCVlT5KVvuyfC4H+HzeGmu9201BVyihJwKdcKPq+n/aY5FUVxNTgtI9f8wIbmfAja oT1pjXSp+dszakA98fhONM98pOq723o/1ZGMZukyXFfsDGtA3BB79HoopHKujLGWAGskzClwTjRQ xBqxh/U/lL1pc+0xPWikTNCmtziCOvv0KA0arDOMQlyFvImzX6oGVgE4ksKQYbMZ3Ikw6L1Rv1J+ FvN0aNwOKgL2ztBRYscUGcQvA0Zo1fGCAn/BLEJvQYShWKeKqjyncVGoXFsz2AcuFKe1pwETSsN6 OZncjy32e4ktgs07cWBfx0v62b8md36jau+B6RVnnodaA8++oXl3FRwiEW8XfXWIjy4umIv93tb8 8ekYsfOfWkTSewZYXGoqe4RtK80ulMHb/dh2FZQIFyRdN4HOmB4FYO5sEYFr9YjHLmDkrUgNodJC XCeMe4BO4iaxUQARAQABzRdtYXJrdXMucHJvYnN0QHBvc3Rlby5kZcLBkQQTAQgAOxYhBIJ0GMT0 rFjncjDEczR2H/jnrUPSBQJog714AhsDBQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJEDR2 H/jnrUPSgdkQAISaTk2D345ehXEkn5z2yUEjaVjHIE7ziqRaOgn/QanCgeTUinIv6L6QXUFvvIfH 1OLPwQ1hfvEg9NnNLyFezWSy6jvoVBTIPqicD/r3FkithnQ1IDkdSjrarPMxJkvuh3l7XZHo49GV HQ8i5zh5w4YISrcEtE99lJisvni2Jqx7we5tey9voQFDyM8jxlSWv3pmoUTCtBkX/eKHJXosgsuS B4TGDCVPOjla/emI5c9MhMG7O4WEEmoSdPbmraPw66YZD6uLyhV4DPHbiDWRzXWnClHSyjB9rky9 lausFxogvu4l9H+KDsXIadNDWdLdu1/enS/wDd9zh5S78rY2jeXaG4mnf4seEKamZ7KQ6FIHrcyP ezdDzssPQcTQcGRMQzCn6wP3tlGk7rsfmyHMlFqdRoNNv+ZER/OkmZFPW655zRfbMi0vtrqK2Awm 9ggobb1oktfd9PPNXMUY+DNVlgR2G7jLnenSoQausLUm0pHoNE8TWFv851Y6SOYnvn488sP1Tki5 F3rKwclawQFHUXTCQw+QSh9ay8xgnNZfH+u9NY7w3gPoeKBOAFcBc2BtzcgekeWS8qgEmm2/oNFV G0ivPQbRx8FjRKbuF7g3YhgNZZ0ac8FneuUtJ2PkSIFTZhaAiC0utvxk0ndmWFiW4acEkMZGrLaM L2zWNjrqwsD2zsFNBGiDvXgBEADCXQy1n7wjRxG12DOVADawjghKcG+5LtEf31WftHKLFbp/HArj BhkT6mj+CCI1ClqY+FYU5CK/s0ScMfLxRGLZ0Ktzawb78vOgBVFT3yB1yWBTewsAXdqNqRooaUNo 8cG/NNJLjhccH/7PO/FWX5qftOVUJ/AIsAhKQJ18Tc8Ik73v427EDxuKb9mTAnYQFA3Ev3hAiVbO 6Rv39amVOfJ8sqwiSUGidj2Fctg2aB5JbeMln0KCUbTD1LhEFepeKypfofAXQbGwaCjAhmkWy/q3 IT1mUrPxOngbxdRoOx1tGUC0HCMUW1sFaJgQPMmDcR0JGPOpgsKnitsSnN7ShcCr1buel7vLnUMD +TAZ5opdoF6HjAvAnBQaijtK6minkrM0seNXnCg0KkV8xhMNa6zCs1rq4GgjNLJue2EmuyHooHA4 7JMoLVHcxVeuNTp6K2+XRx0Pk4e2Lj8IVy9yEYyrywEOC5XRW37KJjsiOAsumi1rkvM7QREWgUDe Xs0+RpxI3QrrANh71fLMRo7LKRF3Gvw13NVCCC9ea20P4PwhgWKStkwO2NO+YJsAoS1QycMi/vKu 0EHhknYXamaSV50oZzHKmX56vEeJHTcngrM8R1SwJCYopCx9gkz90bTVYlitJa5hloWTYeMD7FNj Y6jfVSzgM/K4gMgUNDW/PPGeMwARAQABwsF2BBgBCAAgFiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IF AmiDvXgCGwwACgkQNHYf+OetQ9LHDBAAhk+ab8+WrbS/b1/gYW3q1KDiXU719nCtfkUVXKidW5Ec Idlr5HGt8ilLoxSWT2Zi368iHCXS0WenGgPwlv8ifvB7TOZiiTDZROZkXjEBmU4nYjJ7GymawpWv oQwjMsPuq6ysbzWtOZ7eILx7cI0FjQeJ/Q2baRJub0uAZNwBOxCkAS6lpk5Fntd2u8CWmDQo4SYp xeuQ+pwkp0yEP30RhN2BO2DXiBEGSZSYh+ioGbCHQPIV3iVj0h6lcCPOqopZqyeCfigeacBI0nvN jHWz/spzF3+4OS+3RJvoHtAQmProxyGib8iVsTxgZO3UUi4TSODeEt0i0kHSPY4sCciOyXfAyYoD DFqhRjOEwBBxhr+scU4C1T2AflozvDwq3VSONjrKJUkhd8+WsdXxMdPFgBQuiKKwUy11mz6KQfcR wmDehF3UaUoxa+YIhWPbKmycxuX/D8SvnqavzAeAL1OcRbEI/HsoroVlEFbBRNBZLJUlnTPs8ZcU 4+8rq5YX1GUrJL3jf6SAfSgO7UdkEET3PdcKFYtS+ruV1Cp5V0q4kCfI5jk25iiz8grM2wOzVSsc l1mEkhiEPH87HP0whhb544iioSnumd3HJKL7dzhRegsMizatupp8D65A2JziW0WKopa1iw9fti3A aBeNN4ijKZchBXHPgVx+YtWRHfcm4l8= OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt On device unbind, the pointer to the driver data (`PrivateData`) will first be set to NULL by `drvdata_obtain` and only after that the serdev device will be closed by Drop. Thus there is a small window in which the serdev device is still open, but the pointer to the driver data is NULL. Therefore it is possible that `receive_buf_callback` might try to access the `active` mutex on a null pointer. Add function `drvdata_drop` that leaves the pointer to the driver data valid until the Drop has completed. Use it in the post unbind callback. Fixes: 99f59aa82341 ("rust: add basic serial device bus abstractions") Reported-by: Sashiko Bot Closes: https://lore.kernel.org/linux-serial/20260905000836.C8FC91F00A3D@smtp.kernel.org/ Signed-off-by: Markus Probst --- rust/kernel/device.rs | 27 +++++++++++++++++++++++++++ rust/kernel/driver.rs | 2 +- 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 2291d85b6849..3886cc713c28 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -219,6 +219,7 @@ pub fn set_drvdata(&self, data: impl PinInit) -> Result { /// /// - The type `T` must match the type of the `ForeignOwnable` previously stored by /// [`Device::set_drvdata`]. + /// - Must only be called before the device is fully unbound. pub(crate) unsafe fn drvdata_obtain(&self) -> Option>> { // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`. let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) }; @@ -236,6 +237,32 @@ pub(crate) unsafe fn drvdata_obtain(&self) -> Option>> { // in `into_foreign()`. Some(unsafe { Pin::>::from_foreign(ptr.cast()) }) } + + /// Drop the private data stored in this [`Device`]. + /// + /// The pointer to the private data remains valid until the drop is complete. + /// + /// # Safety + /// + /// - The type `T` must match the type of the `ForeignOwnable` previously stored by + /// [`Device::set_drvdata`]. + pub(crate) unsafe fn drvdata_drop(&self) { + // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`. + let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) }; + + if ptr.is_null() { + return; + } + + // SAFETY: + // - If `ptr` is not NULL, it comes from a previous call to `into_foreign()`. + // - `dev_get_drvdata()` guarantees to return the same pointer given to `dev_set_drvdata()` + // in `into_foreign()`. + drop(unsafe { Pin::>::from_foreign(ptr.cast()) }); + + // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`. + unsafe { bindings::dev_set_drvdata(self.as_raw(), core::ptr::null_mut()) }; + } } impl Device { diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs index c9c74c4dde8f..83410141ef1c 100644 --- a/rust/kernel/driver.rs +++ b/rust/kernel/driver.rs @@ -204,7 +204,7 @@ extern "C" fn post_unbind_callback(dev: *mut bindings::device) { // // SAFETY: By the safety requirements of the `Driver` trait, `T::DriverData` is the // driver's bus device private data type. - drop(unsafe { dev.drvdata_obtain::>() }); + unsafe { dev.drvdata_drop::>() }; } /// Attach generic `struct device_driver` callbacks. -- 2.55.0