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From f4f50ceea8e8852b8c3ac73f5807d8b54b735c3e Mon Sep 17 00:00:00 2001
From: Chris Liddell <chris.liddell@artifex.com>
Date: Tue, 21 Aug 2018 20:17:05 +0100
Subject: [PATCH 5/5] Bug 699657: properly apply file permissions to .tempfile
CVE: CVE-2018-15908
Upstream-Status: Backport [git://git.ghostscript.com/ghostpdl.git]
Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
---
psi/zfile.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/psi/zfile.c b/psi/zfile.c
index a0acd5a..19996b0 100644
--- a/psi/zfile.c
+++ b/psi/zfile.c
@@ -134,7 +134,7 @@ check_file_permissions_reduced(i_ctx_t *i_ctx_p, const char *fname, int len,
/* we're protecting arbitrary file system accesses, not Postscript device accesses.
* Although, note that %pipe% is explicitly checked for and disallowed elsewhere
*/
- if (iodev != iodev_default(imemory)) {
+ if (iodev && iodev != iodev_default(imemory)) {
return 0;
}
@@ -734,7 +734,23 @@ ztempfile(i_ctx_t *i_ctx_p)
}
if (gp_file_name_is_absolute(pstr, strlen(pstr))) {
- if (check_file_permissions(i_ctx_p, pstr, strlen(pstr),
+ int plen = strlen(pstr);
+ const char *sep = gp_file_name_separator();
+#ifdef DEBUG
+ int seplen = strlen(sep);
+ if (seplen != 1)
+ return_error(gs_error_Fatal);
+#endif
+ /* strip off the file name prefix, leave just the directory name
+ * so we can check if we are allowed to write to it
+ */
+ for ( ; plen >=0; plen--) {
+ if (pstr[plen] == sep[0])
+ break;
+ }
+ memcpy(fname, pstr, plen);
+ fname[plen] = '\0';
+ if (check_file_permissions(i_ctx_p, fname, strlen(fname),
NULL, "PermitFileWriting") < 0) {
code = gs_note_error(gs_error_invalidfileaccess);
goto done;
--
2.8.1
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