Wayland: Fix "heap-buffer-overflow" error

- replace strchr() with memchr() because buffer is not nul-terminated
- fix '*(p+1)' potentially accessing memory out of bounds

This fix also prevents
- multiple memmove() calls
- multiple searches from the beginning of the string
This commit is contained in:
Albrecht Schlosser 2023-01-13 16:36:16 +01:00
parent 54e75dc902
commit a4b33f8e76

View File

@ -1,7 +1,7 @@
//
// Wayland-specific code for clipboard and drag-n-drop support.
//
// Copyright 1998-2022 by Bill Spitzak and others.
// Copyright 1998-2023 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
@ -22,14 +22,15 @@
# include <FL/Fl_Window.H>
# include <FL/Fl_Shared_Image.H>
# include <FL/Fl_Image_Surface.H>
# include <stdio.h>
# include <stdlib.h>
# include "../../flstring.h"
# include "Fl_Wayland_Screen_Driver.H"
# include "Fl_Wayland_Window_Driver.H"
# include "../Unix/Fl_Unix_System_Driver.H"
# include "Fl_Wayland_Graphics_Driver.H"
# include "../../flstring.h" // includes <string.h>
# include <errno.h>
# include <stdio.h>
# include <stdlib.h>
////////////////////////////////////////////////////////////////
@ -319,17 +320,27 @@ static void data_device_handle_selection(void *data, struct wl_data_device *data
}
static size_t convert_crlf(char *s, size_t len)
{ // turn \r characters into \n and "\r\n" sequences into \n:
char *p;
size_t l = len;
while ((p = strchr(s, '\r'))) {
if (*(p+1) == '\n') {
memmove(p, p+1, l-(p-s));
len--; l--;
} else *p = '\n';
l -= p-s;
s = p + 1;
// turn '\r' characters into '\n' and "\r\n" sequences into '\n'
// returns new length
static size_t convert_crlf(char *s, size_t len) {
char *src = (char *)memchr(s, '\r', len); // find first `\r` in buffer
if (src) {
char *dst = src;
char *end = s + len;
while (src < end) {
if (*src == '\r') {
if (src + 1 < end && *(src + 1) == '\n') {
src++; // skip '\r'
continue;
} else {
*dst++ = '\n'; // replace single '\r' with '\n'
}
} else {
*dst++ = *src;
}
src++;
}
return (dst - s);
}
return len;
}