From: Arjun Shankar <arjun@redhat.com>
Date: Wed, 4 Nov 2020 11:19:38 +0000 (+0100)
Subject: [PATCH] iconv: Accept redundant shift sequences in IBM1364 [BZ #26224]
X-Git-Tag: archive/raspbian/2.28-10+rpi1+deb10u4^2~15
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=1655713bef79c5ac88d782eb2a11bdf4e0d8eb7d;p=glibc.git

[PATCH] iconv: Accept redundant shift sequences in IBM1364 [BZ #26224]

The IBM1364, IBM1371, IBM1388, IBM1390 and IBM1399 character sets
share converter logic (iconvdata/ibm1364.c) which would reject
redundant shift sequences when processing input in these character
sets.  This led to a hang in the iconv program (CVE-2020-27618).

This commit adjusts the converter to ignore redundant shift sequences
and adds test cases for iconv_prog hangs that would be triggered upon
their rejection.  This brings the implementation in line with other
converters that also ignore redundant shift sequences (e.g. IBM930
etc., fixed in commit 692de4b3960d).

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

Beware that in the Debian build, tst-iconv_prog.sh fails to pick up the built
IBM1364.so and tests the system one instead. As such, the test case will fail
on the initial build, but succeed on subsequent ones.


Gbp-Pq: Topic all
Gbp-Pq: Name git-CVE-2020-27618-iconv-Accept-redundant-shift-sequences-in-IBM1364-BZ.diff
---

diff --git a/iconv/tst-iconv_prog.sh b/iconv/tst-iconv_prog.sh
index 8298136b7..d8db7b335 100644
--- a/iconv/tst-iconv_prog.sh
+++ b/iconv/tst-iconv_prog.sh
@@ -102,12 +102,16 @@ hangarray=(
 "\x00\x80;-c;IBM1161;UTF-8//TRANSLIT//IGNORE"
 "\x00\xdb;-c;IBM1162;UTF-8//TRANSLIT//IGNORE"
 "\x00\x70;-c;IBM12712;UTF-8//TRANSLIT//IGNORE"
-# These are known hangs that are yet to be fixed:
-# "\x00\x0f;-c;IBM1364;UTF-8"
-# "\x00\x0f;-c;IBM1371;UTF-8"
-# "\x00\x0f;-c;IBM1388;UTF-8"
-# "\x00\x0f;-c;IBM1390;UTF-8"
-# "\x00\x0f;-c;IBM1399;UTF-8"
+"\x00\x0f;-c;IBM1364;UTF-8"
+"\x0e\x0e;-c;IBM1364;UTF-8"
+"\x00\x0f;-c;IBM1371;UTF-8"
+"\x0e\x0e;-c;IBM1371;UTF-8"
+"\x00\x0f;-c;IBM1388;UTF-8"
+"\x0e\x0e;-c;IBM1388;UTF-8"
+"\x00\x0f;-c;IBM1390;UTF-8"
+"\x0e\x0e;-c;IBM1390;UTF-8"
+"\x00\x0f;-c;IBM1399;UTF-8"
+"\x0e\x0e;-c;IBM1399;UTF-8"
 "\x00\x53;-c;IBM16804;UTF-8//TRANSLIT//IGNORE"
 "\x00\x41;-c;IBM274;UTF-8//TRANSLIT//IGNORE"
 "\x00\x41;-c;IBM275;UTF-8//TRANSLIT//IGNORE"
diff --git a/iconvdata/ibm1364.c b/iconvdata/ibm1364.c
index 517fe6081..ecc3f8ddd 100644
--- a/iconvdata/ibm1364.c
+++ b/iconvdata/ibm1364.c
@@ -158,24 +158,14 @@ enum
 									      \
     if (__builtin_expect (ch, 0) == SO)					      \
       {									      \
-	/* Shift OUT, change to DBCS converter.  */			      \
-	if (curcs == db)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift OUT, change to DBCS converter (redundant escape okay).  */   \
 	curcs = db;							      \
 	++inptr;							      \
 	continue;							      \
       }									      \
     if (__builtin_expect (ch, 0) == SI)					      \
       {									      \
-	/* Shift IN, change to SBCS converter.  */			      \
-	if (curcs == sb)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift IN, change to SBCS converter (redundant escape okay).  */    \
 	curcs = sb;							      \
 	++inptr;							      \
 	continue;							      \