1From 123eaff0d5d1aebe128295959435b9ca5909c26d Mon Sep 17 00:00:00 2001 2From: Andreas Gruenbacher <agruen@gnu.org> 3Date: Fri, 6 Apr 2018 12:14:49 +0200 4Subject: [PATCH] Fix arbitrary command execution in ed-style patches 5 (CVE-2018-1000156) 6 7* src/pch.c (do_ed_script): Write ed script to a temporary file instead 8of piping it to ed: this will cause ed to abort on invalid commands 9instead of rejecting them and carrying on. 10* tests/ed-style: New test case. 11* tests/Makefile.am (TESTS): Add test case. 12 13[baruch: drop test hunks to avoid autoreconf] 14Signed-off-by: Baruch Siach <baruch@tkos.co.il> 15--- 16Upstream status: commit 123eaff0d5d1 17 18 src/pch.c | 91 ++++++++++++++++++++++++++++++++++++++++--------------- 19 tests/Makefile.am | 1 + 20 tests/ed-style | 41 +++++++++++++++++++++++++ 21 3 files changed, 108 insertions(+), 25 deletions(-) 22 create mode 100644 tests/ed-style 23 24diff --git a/src/pch.c b/src/pch.c 25index 0c5cc2623079..4fd5a05a6f5c 100644 26--- a/src/pch.c 27+++ b/src/pch.c 28@@ -33,6 +33,7 @@ 29 # include <io.h> 30 #endif 31 #include <safe.h> 32+#include <sys/wait.h> 33 34 #define INITHUNKMAX 125 /* initial dynamic allocation size */ 35 36@@ -2389,24 +2390,28 @@ do_ed_script (char const *inname, char const *outname, 37 static char const editor_program[] = EDITOR_PROGRAM; 38 39 file_offset beginning_of_this_line; 40- FILE *pipefp = 0; 41 size_t chars_read; 42+ FILE *tmpfp = 0; 43+ char const *tmpname; 44+ int tmpfd; 45+ pid_t pid; 46+ 47+ if (! dry_run && ! skip_rest_of_patch) 48+ { 49+ /* Write ed script to a temporary file. This causes ed to abort on 50+ invalid commands such as when line numbers or ranges exceed the 51+ number of available lines. When ed reads from a pipe, it rejects 52+ invalid commands and treats the next line as a new command, which 53+ can lead to arbitrary command execution. */ 54+ 55+ tmpfd = make_tempfile (&tmpname, 'e', NULL, O_RDWR | O_BINARY, 0); 56+ if (tmpfd == -1) 57+ pfatal ("Can't create temporary file %s", quotearg (tmpname)); 58+ tmpfp = fdopen (tmpfd, "w+b"); 59+ if (! tmpfp) 60+ pfatal ("Can't open stream for file %s", quotearg (tmpname)); 61+ } 62 63- if (! dry_run && ! skip_rest_of_patch) { 64- int exclusive = *outname_needs_removal ? 0 : O_EXCL; 65- if (inerrno != ENOENT) 66- { 67- *outname_needs_removal = true; 68- copy_file (inname, outname, 0, exclusive, instat.st_mode, true); 69- } 70- sprintf (buf, "%s %s%s", editor_program, 71- verbosity == VERBOSE ? "" : "- ", 72- outname); 73- fflush (stdout); 74- pipefp = popen(buf, binary_transput ? "wb" : "w"); 75- if (!pipefp) 76- pfatal ("Can't open pipe to %s", quotearg (buf)); 77- } 78 for (;;) { 79 char ed_command_letter; 80 beginning_of_this_line = file_tell (pfp); 81@@ -2417,14 +2422,14 @@ do_ed_script (char const *inname, char const *outname, 82 } 83 ed_command_letter = get_ed_command_letter (buf); 84 if (ed_command_letter) { 85- if (pipefp) 86- if (! fwrite (buf, sizeof *buf, chars_read, pipefp)) 87+ if (tmpfp) 88+ if (! fwrite (buf, sizeof *buf, chars_read, tmpfp)) 89 write_fatal (); 90 if (ed_command_letter != 'd' && ed_command_letter != 's') { 91 p_pass_comments_through = true; 92 while ((chars_read = get_line ()) != 0) { 93- if (pipefp) 94- if (! fwrite (buf, sizeof *buf, chars_read, pipefp)) 95+ if (tmpfp) 96+ if (! fwrite (buf, sizeof *buf, chars_read, tmpfp)) 97 write_fatal (); 98 if (chars_read == 2 && strEQ (buf, ".\n")) 99 break; 100@@ -2437,13 +2442,49 @@ do_ed_script (char const *inname, char const *outname, 101 break; 102 } 103 } 104- if (!pipefp) 105+ if (!tmpfp) 106 return; 107- if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, pipefp) == 0 108- || fflush (pipefp) != 0) 109+ if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, tmpfp) == 0 110+ || fflush (tmpfp) != 0) 111 write_fatal (); 112- if (pclose (pipefp) != 0) 113- fatal ("%s FAILED", editor_program); 114+ 115+ if (lseek (tmpfd, 0, SEEK_SET) == -1) 116+ pfatal ("Can't rewind to the beginning of file %s", quotearg (tmpname)); 117+ 118+ if (! dry_run && ! skip_rest_of_patch) { 119+ int exclusive = *outname_needs_removal ? 0 : O_EXCL; 120+ *outname_needs_removal = true; 121+ if (inerrno != ENOENT) 122+ { 123+ *outname_needs_removal = true; 124+ copy_file (inname, outname, 0, exclusive, instat.st_mode, true); 125+ } 126+ sprintf (buf, "%s %s%s", editor_program, 127+ verbosity == VERBOSE ? "" : "- ", 128+ outname); 129+ fflush (stdout); 130+ 131+ pid = fork(); 132+ if (pid == -1) 133+ pfatal ("Can't fork"); 134+ else if (pid == 0) 135+ { 136+ dup2 (tmpfd, 0); 137+ execl ("/bin/sh", "sh", "-c", buf, (char *) 0); 138+ _exit (2); 139+ } 140+ else 141+ { 142+ int wstatus; 143+ if (waitpid (pid, &wstatus, 0) == -1 144+ || ! WIFEXITED (wstatus) 145+ || WEXITSTATUS (wstatus) != 0) 146+ fatal ("%s FAILED", editor_program); 147+ } 148+ } 149+ 150+ fclose (tmpfp); 151+ safe_unlink (tmpname); 152 153 if (ofp) 154 { 155-- 1562.16.3 157 158