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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=jRm+kuQX; 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 9D57D606D822; Wed, 4 Nov 2026 17:48:26 +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=jRm+kuQX Received: by smtp.kernel.org (Postfix) with ESMTPSA id 512051F000C1; Wed, 4 Nov 2026 17:48:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793814506; bh=3ZyIQLij17XFBIkY/FnNnjbp2RgAs/rkMBTgRuVD6WA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jRm+kuQXLx3HxqJQ/pjoWlYGnOb5R2cVrI0BxZjs1H9Bw8isgylYtekF6fzwCYam0 GpULB5lXQbyTK/Edh9b2eC4kps+uu7bCEsyidT0bHm7H2HfmOVOP/JWR98p8XKggDV gbR+sBOa4/o7t63orB3vACnwFADp+bNRfAOdtU2Yc/wWPiuGQBbek9DZxI+EgwmNgG KWLc3uoF26LdC4oCj9qcMJD06sucvBwbhfn2X8BjLVTXyfWCytbRIvS8esUEF/ocEj eFEobff+fM/wQhcYScZQ5sJRBVHN2AlsYRDXbqaRDoezJ+0bPS0RQxOsMA9AvIN8D2 a7u52gum9t5KQ== From: Christian Brauner To: linux-fsdevel@vger.kernel.org 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-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever , stable@vger.kernel.org Subject: [PATCH v2 14/51] proc: sysctl: don't stop readdir at an entry that is being unregistered Date: Wed, 4 Nov 2026 18:47:00 +0100 Message-ID: <20261104-work-procfs-bugfixes-v2-14-bbf7d5546809@kernel.org> In-Reply-To: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> References: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> X-Mailing-List: linux-debuggers@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1722; i=brauner@kernel.org; h=from:subject:message-id; bh=6hLGzd3ohIjIvoG2NrLKRAR6DerSlran3UFG44ON0F0=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9zrvAWu/kaD6x96PK3okTN85e99fjn1Pl3U3bGJtnN F1XMW6+3lHKwiDGxSArpsji0G4SLrecp2KzUaYGzBxWJpAhDFycAjCRfk9GhqVlT3f9k3gTlZE2 2Sl7qnRP89Frq6PEfR/pxi6YuOo16wdGhrWT5lf5PEid/zYw+uqn/MXSBi/y5i736erf2r1Ls/F ABg8A X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit proc_sys_fill_cache() creates the inode of an entry that has no dentry yet. Since ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") proc_sys_make_inode() refuses to do that once the table is being unregistered and fails with -ENOENT. readdir takes every table it lists into use and unregister_sysctl_table() marks the table as being unregistered before it waits for readdir to let go of it. So an entry that is unregistered right then makes proc_sys_fill_cache() fail, proc_sys_readdir() stops there and returns 0. If that getdents64() call hadn't emitted anything before that entry userspace sees the end of the directory and never gets the entries behind it. A listing of /proc/sys/net/ipv6/conf can end early that way while a device goes away. So skip an entry whose table is being unregistered, like readdir already skips a link it can't follow. Lookup treats such an entry as gone too since ea5751ccd665 ("proc/sysctl: don't return ENOMEM on lookup when a table is unregistering"). Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- fs/proc/proc_sysctl.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 6c0859c66563..b4a309d49698 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -704,6 +704,9 @@ static bool proc_sys_fill_cache(struct file *file, if (unlikely(res)) { dput(child); + /* skip an entry whose table is being unregistered */ + if (res == ERR_PTR(-ENOENT)) + return true; if (IS_ERR(res)) return false; -- 2.53.0