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>

diff --git a/NEWS b/NEWS
index 4307c4b..0335fb9 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -58,7 +58,9 @@ Changes to build and runtime requirements:
 
 Security related changes:
 
-  [Add security related changes here]
+  CVE-2020-27618: An infinite loop has been fixed in the iconv program when
+  invoked with input containing redundant shift sequences in the IBM1364,
+  IBM1371, IBM1388, IBM1390, or IBM1399 character sets.
 
 The following bugs are resolved with this release:
 

diff --git a/iconv/tst-iconv_prog.sh b/iconv/tst-iconv_prog.sh
index 8298136..d8db7b3 100644 (file)
--- 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 49e7267..521f082 100644 (file)
--- 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;                                                             \