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Fix ctags command execution vulnerability (CVE-2022-45939)
Backported from emacs-29 branch
https://bugs.gentoo.org/883687
commit d48bb4874bc6cd3e69c7a15fc3c91cc141025c51
Author: Xi Lu <lx@shellcodes.org>
Date: Fri Nov 25 14:38:29 2022 +0800
Fixed ctags local command execute vulnerability
--- emacs-28.2/lib-src/etags.c
+++ emacs-28.2/lib-src/etags.c
@@ -382,7 +382,7 @@
static language *get_language_from_langname (const char *);
static void readline (linebuffer *, FILE *);
-static ptrdiff_t readline_internal (linebuffer *, FILE *, char const *);
+static ptrdiff_t readline_internal (linebuffer *, FILE *, char const *, const bool);
static bool nocase_tail (const char *);
static void get_tag (char *, char **);
static void get_lispy_tag (char *);
@@ -406,7 +406,9 @@
static void pfnote (char *, bool, char *, ptrdiff_t, intmax_t, intmax_t);
static void invalidate_nodes (fdesc *, node **);
static void put_entries (node *);
+static void clean_matched_file_tag (char const * const, char const * const);
+static void do_move_file (const char *, const char *);
static char *concat (const char *, const char *, const char *);
static char *skip_spaces (char *);
static char *skip_non_spaces (char *);
@@ -1339,7 +1341,7 @@
if (parsing_stdin)
fatal ("cannot parse standard input "
"AND read file names from it");
- while (readline_internal (&filename_lb, stdin, "-") > 0)
+ while (readline_internal (&filename_lb, stdin, "-", false) > 0)
process_file_name (filename_lb.buffer, lang);
}
else
@@ -1387,9 +1389,6 @@
/* From here on, we are in (CTAGS && !cxref_style) */
if (update)
{
- char *cmd =
- xmalloc (strlen (tagfile) + whatlen_max +
- sizeof "mv..OTAGS;grep -Fv '\t\t' OTAGS >;rm OTAGS");
for (i = 0; i < current_arg; ++i)
{
switch (argbuffer[i].arg_type)
@@ -1400,17 +1399,8 @@
default:
continue; /* the for loop */
}
- char *z = stpcpy (cmd, "mv ");
- z = stpcpy (z, tagfile);
- z = stpcpy (z, " OTAGS;grep -Fv '\t");
- z = stpcpy (z, argbuffer[i].what);
- z = stpcpy (z, "\t' OTAGS >");
- z = stpcpy (z, tagfile);
- strcpy (z, ";rm OTAGS");
- if (system (cmd) != EXIT_SUCCESS)
- fatal ("failed to execute shell command");
+ clean_matched_file_tag (tagfile, argbuffer[i].what);
}
- free (cmd);
append_to_tagfile = true;
}
@@ -1439,6 +1429,51 @@
return EXIT_SUCCESS;
}
+/*
+ * Equivalent to: mv tags OTAGS;grep -Fv ' filename ' OTAGS >tags;rm OTAGS
+ */
+static void
+clean_matched_file_tag (const char* tagfile, const char* match_file_name)
+{
+ FILE *otags_f = fopen ("OTAGS", "wb");
+ FILE *tag_f = fopen (tagfile, "rb");
+
+ if (otags_f == NULL)
+ pfatal ("OTAGS");
+
+ if (tag_f == NULL)
+ pfatal (tagfile);
+
+ int buf_len = strlen (match_file_name) + sizeof ("\t\t ") + 1;
+ char *buf = xmalloc (buf_len);
+ snprintf (buf, buf_len, "\t%s\t", match_file_name);
+
+ linebuffer line;
+ linebuffer_init (&line);
+ while (readline_internal (&line, tag_f, tagfile, true) > 0)
+ {
+ if (ferror (tag_f))
+ pfatal (tagfile);
+
+ if (strstr (line.buffer, buf) == NULL)
+ {
+ fprintf (otags_f, "%s\n", line.buffer);
+ if (ferror (tag_f))
+ pfatal (tagfile);
+ }
+ }
+ free (buf);
+ free (line.buffer);
+
+ if (fclose (otags_f) == EOF)
+ pfatal ("OTAGS");
+
+ if (fclose (tag_f) == EOF)
+ pfatal (tagfile);
+
+ do_move_file ("OTAGS", tagfile);
+ return;
+}
/*
* Return a compressor given the file name. If EXTPTR is non-zero,
@@ -1822,7 +1857,7 @@
/* Else look for sharp-bang as the first two characters. */
if (parser == NULL
- && readline_internal (&lb, inf, infilename) > 0
+ && readline_internal (&lb, inf, infilename, false) > 0
&& lb.len >= 2
&& lb.buffer[0] == '#'
&& lb.buffer[1] == '!')
@@ -6861,7 +6896,7 @@
if (regexfp == NULL)
pfatal (regexfile);
linebuffer_init (®exbuf);
- while (readline_internal (®exbuf, regexfp, regexfile) > 0)
+ while (readline_internal (®exbuf, regexfp, regexfile, false) > 0)
analyze_regex (regexbuf.buffer);
free (regexbuf.buffer);
if (fclose (regexfp) != 0)
@@ -7209,11 +7244,13 @@
/*
* Read a line of text from `stream' into `lbp', excluding the
- * newline or CR-NL, if any. Return the number of characters read from
- * `stream', which is the length of the line including the newline.
+ * newline or CR-NL (if `leave_cr` is false), if any. Return the
+ * number of characters read from `stream', which is the length
+ * of the line including the newline.
*
- * On DOS or Windows we do not count the CR character, if any before the
- * NL, in the returned length; this mirrors the behavior of Emacs on those
+ * On DOS or Windows, if `leave_cr` is false, we do not count the
+ * CR character, if any before the NL, in the returned length;
+ * this mirrors the behavior of Emacs on those
* platforms (for text files, it translates CR-NL to NL as it reads in the
* file).
*
@@ -7221,7 +7258,7 @@
* appended to `filebuf'.
*/
static ptrdiff_t
-readline_internal (linebuffer *lbp, FILE *stream, char const *filename)
+readline_internal (linebuffer *lbp, FILE *stream, char const *filename, const bool leave_cr)
{
char *buffer = lbp->buffer;
char *p = lbp->buffer;
@@ -7251,19 +7288,19 @@
break;
}
if (c == '\n')
- {
- if (p > buffer && p[-1] == '\r')
- {
- p -= 1;
- chars_deleted = 2;
- }
- else
- {
- chars_deleted = 1;
- }
- *p = '\0';
- break;
- }
+ {
+ if (!leave_cr && p > buffer && p[-1] == '\r')
+ {
+ p -= 1;
+ chars_deleted = 2;
+ }
+ else
+ {
+ chars_deleted = 1;
+ }
+ *p = '\0';
+ break;
+ }
*p++ = c;
}
lbp->len = p - buffer;
@@ -7294,7 +7331,7 @@
readline (linebuffer *lbp, FILE *stream)
{
linecharno = charno; /* update global char number of line start */
- ptrdiff_t result = readline_internal (lbp, stream, infilename);
+ ptrdiff_t result = readline_internal (lbp, stream, infilename, false);
lineno += 1; /* increment global line number */
charno += result; /* increment global char number */
@@ -7652,6 +7689,46 @@
return templt;
}
+static void
+do_move_file(const char *src_file, const char *dst_file)
+{
+ if (rename (src_file, dst_file) == 0)
+ return;
+
+ FILE *src_f = fopen (src_file, "rb");
+ FILE *dst_f = fopen (dst_file, "wb");
+
+ if (src_f == NULL)
+ pfatal (src_file);
+
+ if (dst_f == NULL)
+ pfatal (dst_file);
+
+ int c;
+ while ((c = fgetc (src_f)) != EOF)
+ {
+ if (ferror (src_f))
+ pfatal (src_file);
+
+ if (ferror (dst_f))
+ pfatal (dst_file);
+
+ if (fputc (c, dst_f) == EOF)
+ pfatal ("cannot write");
+ }
+
+ if (fclose (src_f) == EOF)
+ pfatal (src_file);
+
+ if (fclose (dst_f) == EOF)
+ pfatal (dst_file);
+
+ if (unlink (src_file) == -1)
+ pfatal ("unlink error");
+
+ return;
+}
+
/* Return a newly allocated string containing the file name of FILE
relative to the absolute directory DIR (which should end with a slash). */
static char *
|