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From 216eb14b558df344b206bf82e2bdaf03a1f2f429 Mon Sep 17 00:00:00 2001
From: Peter Kydas <pk@canva.com>
Date: Tue, 6 Feb 2024 20:03:04 +1100
Subject: fix splinefont shell command injection (#5367)
---
fontforge/splinefont.c | 125 +++++++++++++++++++++++++++++------------
1 file changed, 90 insertions(+), 35 deletions(-)
diff --git a/fontforge/splinefont.c b/fontforge/splinefont.c
index 239fdc035..647daee10 100644
--- a/fontforge/splinefont.c
+++ b/fontforge/splinefont.c
@@ -788,11 +788,14 @@ return( name );
char *Unarchive(char *name, char **_archivedir) {
char *dir = getenv("TMPDIR");
- char *pt, *archivedir, *listfile, *listcommand, *unarchivecmd, *desiredfile;
+ char *pt, *archivedir, *listfile, *desiredfile;
char *finalfile;
int i;
int doall=false;
static int cnt=0;
+ gchar *command[5];
+ gchar *stdoutresponse = NULL;
+ gchar *stderrresponse = NULL;
*_archivedir = NULL;
@@ -827,18 +830,30 @@ return( NULL );
listfile = malloc(strlen(archivedir)+strlen("/" TOC_NAME)+1);
sprintf( listfile, "%s/" TOC_NAME, archivedir );
- listcommand = malloc( strlen(archivers[i].unarchive) + 1 +
- strlen( archivers[i].listargs) + 1 +
- strlen( name ) + 3 +
- strlen( listfile ) +4 );
- sprintf( listcommand, "%s %s %s > %s", archivers[i].unarchive,
- archivers[i].listargs, name, listfile );
- if ( system(listcommand)!=0 ) {
- free(listcommand); free(listfile);
- ArchiveCleanup(archivedir);
-return( NULL );
- }
- free(listcommand);
+ command[0] = archivers[i].unarchive;
+ command[1] = archivers[i].listargs;
+ command[2] = name;
+ command[3] = NULL; // command args need to be NULL-terminated
+
+ if ( g_spawn_sync(
+ NULL,
+ command,
+ NULL,
+ G_SPAWN_SEARCH_PATH,
+ NULL,
+ NULL,
+ &stdoutresponse,
+ &stderrresponse,
+ NULL,
+ NULL
+ ) == FALSE) { // did not successfully execute
+ ArchiveCleanup(archivedir);
+ return( NULL );
+ }
+ // Write out the listfile to be read in later
+ FILE *fp = fopen(listfile, "wb");
+ fwrite(stdoutresponse, strlen(stdoutresponse), 1, fp);
+ fclose(fp);
desiredfile = ArchiveParseTOC(listfile, archivers[i].ars, &doall);
free(listfile);
@@ -847,22 +862,28 @@ return( NULL );
return( NULL );
}
- /* I tried sending everything to stdout, but that doesn't work if the */
- /* output is a directory file (ufo, sfdir) */
- unarchivecmd = malloc( strlen(archivers[i].unarchive) + 1 +
- strlen( archivers[i].listargs) + 1 +
- strlen( name ) + 1 +
- strlen( desiredfile ) + 3 +
- strlen( archivedir ) + 30 );
- sprintf( unarchivecmd, "( cd %s ; %s %s %s %s ) > /dev/null", archivedir,
- archivers[i].unarchive,
- archivers[i].extractargs, name, doall ? "" : desiredfile );
- if ( system(unarchivecmd)!=0 ) {
- free(unarchivecmd); free(desiredfile);
- ArchiveCleanup(archivedir);
-return( NULL );
+ command[0] = archivers[i].unarchive;
+ command[1] = archivers[i].extractargs;
+ command[2] = name;
+ command[3] = doall ? "" : desiredfile;
+ command[4] = NULL;
+
+ if ( g_spawn_sync(
+ (gchar*)archivedir,
+ command,
+ NULL,
+ G_SPAWN_SEARCH_PATH,
+ NULL,
+ NULL,
+ &stdoutresponse,
+ &stderrresponse,
+ NULL,
+ NULL
+ ) == FALSE) { // did not successfully execute
+ free(desiredfile);
+ ArchiveCleanup(archivedir);
+ return( NULL );
}
- free(unarchivecmd);
finalfile = malloc( strlen(archivedir) + 1 + strlen(desiredfile) + 1);
sprintf( finalfile, "%s/%s", archivedir, desiredfile );
@@ -885,20 +906,54 @@ struct compressors compressors[] = {
char *Decompress(char *name, int compression) {
char *dir = getenv("TMPDIR");
- char buf[1500];
char *tmpfn;
-
+ gchar *command[4];
+ gint stdout_pipe;
+ gchar buffer[4096];
+ gssize bytes_read;
+ GByteArray *binary_data = g_byte_array_new();
+
if ( dir==NULL ) dir = P_tmpdir;
tmpfn = malloc(strlen(dir)+strlen(GFileNameTail(name))+2);
strcpy(tmpfn,dir);
strcat(tmpfn,"/");
strcat(tmpfn,GFileNameTail(name));
*strrchr(tmpfn,'.') = '\0';
- snprintf( buf, sizeof(buf), "%s < %s > %s", compressors[compression].decomp, name, tmpfn );
- if ( system(buf)==0 )
-return( tmpfn );
- free(tmpfn);
-return( NULL );
+
+ command[0] = compressors[compression].decomp;
+ command[1] = "-c";
+ command[2] = name;
+ command[3] = NULL;
+
+ // Have to use async because g_spawn_sync doesn't handle nul-bytes in the output (which happens with binary data)
+ if (g_spawn_async_with_pipes(
+ NULL,
+ command,
+ NULL,
+ G_SPAWN_DO_NOT_REAP_CHILD | G_SPAWN_SEARCH_PATH,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
+ &stdout_pipe,
+ NULL,
+ NULL) == FALSE) {
+ //command has failed
+ return( NULL );
+ }
+
+ // Read binary data from pipe and output to file
+ while ((bytes_read = read(stdout_pipe, buffer, sizeof(buffer))) > 0) {
+ g_byte_array_append(binary_data, (guint8 *)buffer, bytes_read);
+ }
+ close(stdout_pipe);
+
+ FILE *fp = fopen(tmpfn, "wb");
+ fwrite(binary_data->data, sizeof(gchar), binary_data->len, fp);
+ fclose(fp);
+ g_byte_array_free(binary_data, TRUE);
+
+ return(tmpfn);
}
static char *ForceFileToHaveName(FILE *file, char *exten) {
--
2.30.2
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