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82b2f1993b
ttyname_r() passed the caller buffer straight to fcntl(F_GETPATH) whenever buflen >= TTY_NAME_MAX, but every FIOC_FILEPATH handler writes the path bounded by PATH_MAX and ignores the caller buffer size. A tty registered under a nested /dev path, or reached through rpmsgfs, has a path longer than TTY_NAME_MAX and overwrote the caller buffer, silently corrupting memory behind a zero return code. The small-buffer branch had the same defect against its own stack local char name[TTY_NAME_MAX]. Gate the direct write on PATH_MAX instead and stage the path through a PATH_MAX path buffer obtained via lib_get_tempbuffer(), returning ERANGE when it does not fit. Verified on sim:nsh with a test driver registered at an 85-character tty path: pre-fix, ttyname_r(buf, TTY_NAME_MAX) returned 0 and smashed the canaries behind the buffer, and the small-buffer branch panicked; post-fix both cases return ERANGE with the canaries intact. Assisted-by: Claude Code (glm-5.3) <claude@anthropic.com> Signed-off-by: Junbo Zheng <zhengjunbo1@xiaomi.com>
100 lines
3.3 KiB
C
100 lines
3.3 KiB
C
/****************************************************************************
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* libs/libc/termios/lib_ttynamer.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <errno.h>
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#include <fcntl.h>
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#include <string.h>
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#include <unistd.h>
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#include <nuttx/lib/lib.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ttyname_r
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*
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* Description:
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* The ttyname_r() function shall store the null-terminated pathname of
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* the terminal associated with the file descriptor fildes in the
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* character array referenced by name. The array is namesize characters
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* long and should have space for the name and the terminating null
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* character. The maximum length of the terminal name shall be
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* {TTY_NAME_MAX}.
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*
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* Input Parameters:
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* fd - The 'fd' argument is an open file descriptor associated with
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* a terminal.
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* buf - Caller provided buffer to hold tty name.
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* buflen - The size of the caller-provided buffer.
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*
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* Returned Value:
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* If successful, the ttyname_r() function shall return zero.
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* Otherwise, an error number shall be returned to indicate the error.
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*
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****************************************************************************/
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int ttyname_r(int fd, FAR char *buf, size_t buflen)
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{
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if (!isatty(fd))
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{
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return ENOTTY;
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}
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/* The F_GETPATH handler copies the file path into the caller buffer
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* bounded by PATH_MAX, not by any tty-specific limit, so the path must
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* always land in a PATH_MAX-sized buffer first. Only a caller buffer
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* of that size can receive it directly.
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*/
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if (buflen >= PATH_MAX)
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{
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return fcntl(fd, F_GETPATH, buf) < 0 ? get_errno() : 0;
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}
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else
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{
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FAR char *path = lib_get_tempbuffer(PATH_MAX);
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int ret;
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if (fcntl(fd, F_GETPATH, path) < 0)
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{
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ret = get_errno();
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}
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else if (strlen(path) >= buflen)
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{
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ret = ERANGE;
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}
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else
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{
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strlcpy(buf, path, buflen);
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ret = OK;
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}
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lib_put_tempbuffer(path);
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return ret;
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}
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}
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