From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 44CF2414A2C; Thu, 16 Jul 2026 13:47:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784209644; cv=none; b=sl0X4y7/A8vIHINMLat6YEvJ/rm1fPoHkSXALpxkNF125fFbxlpzC+S4lZcE2l3DQoWLe+1Y4VAZTYBq6CuUpjtk/EOWIRO5pCO6z2ZsoSuJH2WIgASevmfsmG/GlzcJw9Bwk4zY1U9kWNYeE7472k5xlzJRnXCNzGQH7KKrE1M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784209644; c=relaxed/simple; bh=EtTun28iTL9xTmASbigVtgEQNwmg8TEQ6PUiqmD6AGg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cCTzPX+j2eIkayhTpcKZj6ysA8Smdd+IYKtvidkNbjcxmTFidNZkDHfVreH0k/4t5sjPn2/8R9IcxKwkxnSLhPLd1Y6aAarPSHyhhwGbMyW6Z2mhG3ovn9W7q/6rBxnWYdV3EMsYRUXTtv27k7woLPowB/EbGkm52IJ81xRQoYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bU4Yy/1m; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bU4Yy/1m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 190DF1F000E9; Thu, 16 Jul 2026 13:47:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784209636; bh=ib5Vgtb0GKI2seR/K6Q0hafO+b0bLM0nlFFwTLObwTU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bU4Yy/1mWnAraLnHbgLoBLvZQCt4pF845rJ4OSbwanzqH7NgZoQxq2c7CyI50ecfr J9OGJqnrVD8PdUQXDavK2hECjy6ng9zcdYAtV7Cnd4EXMh4XLVE6tPmlRncCFN3yPM UBPM7bitVmvFWQO6CVQwHcQjGNuYFolaAuqJIFx0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gil Portnoy , Namjae Jeon , Steve French Subject: [PATCH 7.1 218/518] ksmbd: add a permission check for FSCTL_SET_ZERO_DATA Date: Thu, 16 Jul 2026 15:28:06 +0200 Message-ID: <20260716133052.586063119@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133047.772246337@linuxfoundation.org> References: <20260716133047.772246337@linuxfoundation.org> User-Agent: quilt/0.69 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-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gil Portnoy commit 3320ba068198adc144c89d6661b805acce01735b upstream. FSCTL_SET_ZERO_DATA in smb2_ioctl() destroys file data via ksmbd_vfs_zero_data() -> vfs_fallocate(PUNCH_HOLE/ZERO_RANGE) after checking only the share-level KSMBD_TREE_CONN_FLAG_WRITABLE, with no per-handle access check. A handle opened with only FILE_WRITE_ATTRIBUTES still yields an FMODE_WRITE filp (FILE_WRITE_ATTRIBUTES is part of FILE_WRITE_DESIRE_ACCESS_LE, so smb2_create_open_flags() opens it O_WRONLY), so the vfs_fallocate FMODE_WRITE check does not stop it; only the missing fp->daccess gate would. Reproduced on mainline 7.1-rc7 with KASAN by an authenticated SMB client: a FILE_WRITE_ATTRIBUTES-only handle zeroed 4096 bytes of file data it had no FILE_WRITE_DATA right to (6/6; a FILE_READ_DATA-only handle was correctly denied). This is the unfixed sibling of commit cc57232cae23 ("ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE"). Because SET_ZERO_DATA writes data (not an attribute), require FILE_WRITE_DATA. Cc: stable@vger.kernel.org Signed-off-by: Gil Portnoy Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/smb2pdu.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -8487,6 +8487,12 @@ int smb2_ioctl(struct ksmbd_work *work) goto out; } + if (!(fp->daccess & FILE_WRITE_DATA_LE)) { + ksmbd_fd_put(work, fp); + ret = -EACCES; + goto out; + } + ret = ksmbd_vfs_zero_data(work, fp, off, len); ksmbd_fd_put(work, fp); if (ret < 0)