https://github.com/fontforge/fontforge/commit/216eb14b558df344b206bf82e2bdaf03a1f2f429 From 216eb14b558df344b206bf82e2bdaf03a1f2f429 Mon Sep 17 00:00:00 2001 From: Peter Kydas Date: Tue, 6 Feb 2024 20:03:04 +1100 Subject: [PATCH] fix splinefont shell command injection (#5367) --- 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) {