From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4EBA81DE4CD; Tue, 8 Oct 2024 13:02:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728392521; cv=none; b=TTyDqr4SyASMR//6om9tAUg69g4rt3R2Wm16LjACTk1xaXihRi8tiHmlQKS+M9X5mJUP55kmQfaYng68pfaMoEPb3+UWBq10qQ1QhhYFUFzUJFRdfWEBT4auS7fRXxV/qa7AAw4djn1OSBWLu3gQfmRwFOfy6k1TlpbAgM/Ie1Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728392521; c=relaxed/simple; bh=gEUQ9jGuDINRdsI8ltQJUNN06gOHlGYUqRHNDgwNh5I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=tdUydnQn1s2XdPkjXo8bu34Pa5/ka879MUpwrdRDU8MyYAn+zKwPsf4OYCDICRwF9IN5ud2HllyhMq3K4kHYEklP/OztkSK9gSZXcii/lrlpn5zrPSskQ8TiAwITWCwOA7nDq3dgE45P7DDlnrPvdpR0jxMzJZ9oelL6XoKVa1o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tSppBb1c; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="tSppBb1c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5323DC4CEC7; Tue, 8 Oct 2024 13:02:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728392520; bh=gEUQ9jGuDINRdsI8ltQJUNN06gOHlGYUqRHNDgwNh5I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tSppBb1cY4caHhNalQ8/S48cD90+LcLFWOnX/24rCu+l8EgafPjPP9s6Ojm4T9H7V r5u4E/QNM27pCvhbeXPmCH3QYvNxLkFeNZm8SNRSbivs635CCM5Te7HeK5CGo54Gcx dBtQMMe2fxQeJ9QLHw1CZPWaeey+6SRlbSRg/yB0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Joel Granados Subject: [PATCH 6.11 438/558] sysctl: avoid spurious permanent empty tables Date: Tue, 8 Oct 2024 14:07:48 +0200 Message-ID: <20241008115719.506164739@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115702.214071228@linuxfoundation.org> References: <20241008115702.214071228@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Weißschuh commit 559d4c6a9d3b60f239493239070eb304edaea594 upstream. The test if a table is a permanently empty one, inspects the address of the registered ctl_table argument. However as sysctl_mount_point is an empty array and does not occupy and space it can end up sharing an address with another object in memory. If that other object itself is a "struct ctl_table" then registering that table will fail as it's incorrectly recognized as permanently empty. Avoid this issue by adding a dummy element to the array so that is not empty anymore. Explicitly register the table with zero elements as otherwise the dummy element would be recognized as a sentinel element which would lead to a runtime warning from the sysctl core. While the issue seems not being encountered at this time, this seems mostly to be due to luck. Also a future change, constifying sysctl_mount_point and root_table, can reliably trigger this issue on clang 18. Given that empty arrays are non-standard in the first place it seems prudent to avoid them if possible. Fixes: 4a7b29f65094 ("sysctl: move sysctl type to ctl_table_header") Fixes: a35dd3a786f5 ("sysctl: drop now unnecessary out-of-bounds check") Cc: stable@vger.kernel.org Signed-off-by: Thomas Weißschuh Closes: https://lore.kernel.org/oe-lkp/202408051453.f638857e-lkp@intel.com Signed-off-by: Joel Granados Signed-off-by: Greg Kroah-Hartman --- fs/proc/proc_sysctl.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -29,8 +29,13 @@ static const struct inode_operations pro static const struct file_operations proc_sys_dir_file_operations; static const struct inode_operations proc_sys_dir_operations; -/* Support for permanently empty directories */ -static struct ctl_table sysctl_mount_point[] = { }; +/* + * Support for permanently empty directories. + * Must be non-empty to avoid sharing an address with other tables. + */ +static struct ctl_table sysctl_mount_point[] = { + { } +}; /** * register_sysctl_mount_point() - registers a sysctl mount point @@ -42,7 +47,7 @@ static struct ctl_table sysctl_mount_poi */ struct ctl_table_header *register_sysctl_mount_point(const char *path) { - return register_sysctl(path, sysctl_mount_point); + return register_sysctl_sz(path, sysctl_mount_point, 0); } EXPORT_SYMBOL(register_sysctl_mount_point);