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From ac8f49ef90e768a63ed3dca50e2b2c6e8d333bfd Mon Sep 17 00:00:00 2001
From: Qualys Security Advisory <qsa@qualys.com>
Date: Sun, 21 Feb 2021 21:26:53 -0800
Subject: [PATCH 11/29] CVE-2020-28015+28021: New-line injection into spool
header file
---
src/spool_out.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/src/spool_out.c b/src/spool_out.c
index d55895202..9394393d5 100644
--- a/src/spool_out.c
+++ b/src/spool_out.c
@@ -108,6 +108,18 @@ return fd;
* Write the header spool file *
*************************************************/
+static const uschar *
+zap_newlines(const uschar *s)
+{
+uschar *z, *p;
+
+if (Ustrchr(s, '\n') == NULL) return s;
+
+p = z = string_copy(s);
+while ((p = Ustrchr(p, '\n')) != NULL) *p++ = ' ';
+return z;
+}
+
/* Returns the size of the file for success; zero for failure. The file is
written under a temporary name, and then renamed. It's done this way so that it
works with re-writing the file on message deferral as well as for the initial
@@ -210,7 +222,7 @@ if (body_zerocount > 0) fprintf(fp, "-body_zerocount %d\n", body_zerocount);
if (authenticated_id)
fprintf(fp, "-auth_id %s\n", authenticated_id);
if (authenticated_sender)
- fprintf(fp, "-auth_sender %s\n", authenticated_sender);
+ fprintf(fp, "-auth_sender %s\n", zap_newlines(authenticated_sender));
if (f.allow_unqualified_recipient) fprintf(fp, "-allow_unqualified_recipient\n");
if (f.allow_unqualified_sender) fprintf(fp, "-allow_unqualified_sender\n");
@@ -283,19 +295,20 @@ fprintf(fp, "%d\n", recipients_count);
for (i = 0; i < recipients_count; i++)
{
recipient_item *r = recipients_list + i;
+ const uschar *address = zap_newlines(r->address);
DEBUG(D_deliver) debug_printf("DSN: Flags :%d\n", r->dsn_flags);
if (r->pno < 0 && r->errors_to == NULL && r->dsn_flags == 0)
- fprintf(fp, "%s\n", r->address);
+ fprintf(fp, "%s\n", address);
else
{
- uschar * errors_to = r->errors_to ? r->errors_to : US"";
+ const uschar * errors_to = r->errors_to ? zap_newlines(r->errors_to) : US"";
/* for DSN SUPPORT extend exim 4 spool in a compatible way by
adding new values upfront and add flag 0x02 */
uschar * orcpt = r->orcpt ? r->orcpt : US"";
- fprintf(fp, "%s %s %d,%d %s %d,%d#3\n", r->address, orcpt, Ustrlen(orcpt),
+ fprintf(fp, "%s %s %d,%d %s %d,%d#3\n", address, orcpt, Ustrlen(orcpt),
r->dsn_flags, errors_to, Ustrlen(errors_to), r->pno);
}
--
2.30.2
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