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 A5EC21DFFB; Thu, 15 Aug 2024 14:37:23 +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=1723732643; cv=none; b=OD4BkXMzewJ4WLpP7QiDv3PeECTDpdJubWbk3FaDvmKlmSy1lG5Hw0Xf2JVxUWTMQ/wIX3GifHIELB4W7YF7tjaTgHW7U6H9NKFNUzTa5xtsr8WSmX5siKxWx8st5Wlopq+N9J332X0k+yw6+ew/NWqetlSJPLVBgB866irIRoc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723732643; c=relaxed/simple; bh=neQZ21esSGT9WWRN7v33G3UeO/I2VhgNQPHhwV093Ws=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wk5IXn23hFSmtoOadE86Al8rHTY9hkVtc21DTSUEtEq12VtDGjbuz54A9e0rbnd2nCSHEnJBW9Bl7G4x/IDjU21HfRjMh2HPu4vI+wBnJFEcUSmUONkNNFBssigVsy9cD5fr3wLx8EbjgrxMuX2e5eUMs1HRNDEMQV+D7yO3PNc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rmdKgkBS; 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="rmdKgkBS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2E3EAC32786; Thu, 15 Aug 2024 14:37:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723732643; bh=neQZ21esSGT9WWRN7v33G3UeO/I2VhgNQPHhwV093Ws=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rmdKgkBSHu9a5ILJH5Nwtb9N8pSLk3gr5FeykWT/YgX1H4xJ68NjxhFhDU0SoyoB3 SCnWnMIF8dF5acfXpzhsPYVhp0gxEExJwvcS2h4gnL6W3pvBWEZlDvP44JZlrzOs5N ZjyqYFzu0VpO0wuU7rOJUr75FY0j2re+1H7NJijk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Al Viro Subject: [PATCH 5.10 242/352] protect the fetch of ->fd[fd] in do_dup2() from mispredictions Date: Thu, 15 Aug 2024 15:25:08 +0200 Message-ID: <20240815131928.791057254@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131919.196120297@linuxfoundation.org> References: <20240815131919.196120297@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-Transfer-Encoding: 8bit 5.10-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 @@ -1057,6 +1057,7 @@ __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;