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 EB06582D70; Wed, 7 Aug 2024 15:15:05 +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=1723043706; cv=none; b=ETHgNqab5Ys5XiBvltiibbcCkNqwhc7BzPilMFDAPDkjkuvAh+n7Wd8owXpitFhcW0K38jNsMSRswc0nUjT9NXkMvH1xZcg0ikuJySPXvMJkD0kRl9IlE5je9zZm03GtS+WoxWkI2m6sl2yjUhQ8KW5MkRtnw2VS4p1Q1i8Ejvc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723043706; c=relaxed/simple; bh=uFn6ociwLVuUh9NhFczluQWN8lJyjdyiuU3MsIKcEMM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bZzcypWKnZ0689UWgR0OpJxihmaJQhcCZR4g42L5khIlQjgQaGzKpWWxUW7MrFTt4YAiEJFb3bnzCSfmGmjjvrgkNj6nfhwuiulIsXhLAMBri4ZuRJezda8Wqlco3BtD9QAPyo7bqG2x42FWiD3WYIJvddg/9InoxHxQ7Fzb/7w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cYueFgjR; 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="cYueFgjR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CDDAC32781; Wed, 7 Aug 2024 15:15:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723043705; bh=uFn6ociwLVuUh9NhFczluQWN8lJyjdyiuU3MsIKcEMM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cYueFgjRUvXv5x7Du0oph3FZRdBTkU4lNhEdQDdR+yQzIVxxvKCPvpqchOdF7W39x qY8l3zbajFjxEMxF4fCvsXtbXwmbtQ//wmhPaa062epKvg3DxRRTQNiIvJ3Rat7tKI QPmEtRQU2RiaOOC9YlsfT2agQ62/oaovQfXKEOko= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Al Viro Subject: [PATCH 6.1 70/86] protect the fetch of ->fd[fd] in do_dup2() from mispredictions Date: Wed, 7 Aug 2024 17:00:49 +0200 Message-ID: <20240807150041.575513462@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240807150039.247123516@linuxfoundation.org> References: <20240807150039.247123516@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro commit 8aa37bde1a7b645816cda8b80df4753ecf172bf1 upstream. both callers have verified that fd is not greater than ->max_fds; however, misprediction might end up with tofree = fdt->fd[fd]; being speculatively executed. That's wrong for the same reasons why it's wrong in close_fd()/file_close_fd_locked(); the same solution applies - array_index_nospec(fd, fdt->max_fds) could differ from fd only in case of speculative execution on mispredicted path. Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/file.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/file.c +++ b/fs/file.c @@ -1122,6 +1122,7 @@ __releases(&files->file_lock) * tables and this condition does not arise without those. */ fdt = files_fdtable(files); + fd = array_index_nospec(fd, fdt->max_fds); tofree = fdt->fd[fd]; if (!tofree && fd_is_open(fd, fdt)) goto Ebusy;