From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793717290; b=r+H4LFXfOVzVhRWMlZ10Lv1XXCPIdG0cqNqPFNV9/VrIu8uNdJuXmyfpmQopSGNc0Jgm 3CEZXTg9BrPmuEAZTae3fErmvV1hpVr2wfdg1cedyNwmlgyossn6WecIpkpDvhX3FVL4U WYdSHP6g0cx5KumWHvzbU33zZS/QrqwTPliHiqb8lvY0yznCDpUrGOcxN2XDYPKzbKf5K aEgt0c4h7EyevjCAgztE980w3Aporw6GiyP9Iw7rwVDyMRrDBcLvqxqaINgINUhAcFkRn 8jqdJi7ILp3jOZKU6vK9RWGB3vUYX/LmTlqHfEwI17Q/oi+W/kUyee//Hm8PXV6aBuw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793717290; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=8mbFNT8lVL2nvpVsUKgASJ1yFuw1L2kPoKsCbuWRO+8=; b=Lrct8dxy2sMSCDZ2Ov3dGFentbXSUOa0yYni/0YuXXGpIflLmMcDTpoqIfAnLyfkvw1a XecfZIxLcodpZvZ6X8VvvsmO5R8v5eQ++XniphGlsbtOlmBIEqZ3bmMEvc4LQCapFVZVi bh3SmWF71aBwJVxrNiRco3H9ZY+JQNs9WJaRjLDNT1UeNlwcdfbifkie7WkUPzGy1Q8BK fJuND5GiTPvrBxbTjqg2lKQTaKwsPGfg0yeia7tsjF1Mg0jS7Tm5f1gU6JH78dYZLfrts A9imVIPB/LJUhsNC+p6XK00VZK1XNsX8TbolZaJm8d1NOFWCbt/UCqrxpClME2G0Nqw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=epjMvs1d; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB90060A5BD4; Tue, 3 Nov 2026 14:48:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=epjMvs1d Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A6791F000C1; Tue, 3 Nov 2026 14:48:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793717289; bh=8mbFNT8lVL2nvpVsUKgASJ1yFuw1L2kPoKsCbuWRO+8=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=epjMvs1dEdIwrI2DpgBsZGQorVKIJHhwUyrikWAHBc6Kk4cu+6mzN1OvGvUEUPhEM B6AUhqEbvZnjd+L44ByeppapXiuprgTdI5dgYBGzcuPQ4mliSoBdYo9ya2AhybeQeS hLysf5uAjAy1Ce1fGawoITmQs42q0WmndS/BpCcBJHCfp5/P5rgpN0KUvtsPXZ/tyI 1RZJZQTcjxHQ3TMgT1oAPoFy9LwZ7R59bQU8SwJTbZ2VhKizlrum4kIdEP7KLjnN/f n8AAaCBb12w0yRYObxfiHCa2z0CKocMdytuZrknD7LG7ju9D/FRUqPhOPy2fc6VOrS AnhnaOeX0gTFQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH RFC 21/38] proc: let proc_remove() remove the entry it was given Reply-To: sashiko-reviews@lists.linux.dev To: "Christian Brauner" Cc: "Linus Torvalds" , "Jann Horn" , "Josef Bacik" , "Chris Mason" , "Jeff Layton" , NeilBrown , "Eric Dumazet" , "Thomas Gleixner" , "Al Viro" , "Jonathan Corbet" , "Christoph Hellwig" , "Greg Kroah-Hartman" , "Joel Granados" , "Kees Cook" , "Jan Kara" , "Jan Kara" , linux-s390@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, linux-m68k@lists.linux-m68k.org, linux-serial@vger.kernel.org, "Takashi Iwai" , linux-ext4@vger.kernel.org, "Chuck Lever" , tytso@mit.edu, "Heiko Carstens" , "Vasily Gorbik" , "Alexander Gordeev" , "Christian Borntraeger" In-Reply-To: <20261102-work-procfs-bugfixes-v1-21-59422ed3e465@kernel.org> References: <20261102-work-procfs-bugfixes-v1-0-59422ed3e465@kernel.org> <20261102-work-procfs-bugfixes-v1-21-59422ed3e465@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 03 Nov 2026 14:48:07 +0000 X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > proc_remove() looks the entry up by its name in its parent and removes > whatever it finds there: >=20 > remove_proc_subtree(de->name, de->parent); >=20 > If the entry was removed already, say along with its parent, that is > either nothing or a different entry that got the same name in the > meantime, and de->parent may well be gone. Two removals of the same > entry are a bug in the caller, but going by the name turns it into > removing an entry that belongs to somebody else. >=20 > Since commit 895b4c0c79b0 ("fs/proc: fix uaf in proc_readdir_de()") > an entry that was unlinked has an empty rb node. So check for that > under proc_subdir_lock and otherwise remove the entry itself, with the > loop of remove_proc_subtree() moved into a helper both of them use. > Nothing can help a caller that passes an entry that has been freed > already. >=20 > Reported-by: Chris Mason > Fixes: a8ca16ea7b0a ("proc: Supply a function to remove a proc entry by P= DE") > Signed-off-by: Christian Brauner (Amutable) Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261102-work-procf= s-bugfixes-v1-0-59422ed3e465@kernel.org?part=3D21