From 377085a7fd41e01c0c1ad5d1c1f90b59e8257593

From: Markus Kuhn <Markus.Kuhn@cl.cam.ac.uk>

Subject: [PATCH] Fix two DPPRIV buffer overflows and a bug

* jbig.c:jbg_dec_in(): when a BIE with option DPPRIV=1 was received,

  the included private DP table (1728 bytes) was loaded into

  20-byte array s->buffer, creating a buffer overflow vulnerability.

  It is now loaded instead into a malloc'ed temporary buffer.

* jbig.c:jbg_dec_in(): buffer allocated for internal representation

  of private DP table was 1728 bytes long, but must be 6912 bytes long,

  creating another buffer overflow vulnerability.

* jbig.c: a loop in the routines for converting between the internal and

  external representations of a DP table terminated earlier than intended.

  As a result, a private DP table provided to the decoder was not

  interpreted correctly. Likewise, if a user asked the encoder to output

  its standard DP table (which is only useful for testing), the result

  would have been incorrect.

* tstcodec.c: test case for DPPRIV=1 added.

The buffer overflow vulnerability was reported by Florian Weimer (Red Hat)

and has been assigned CVE-2013-6369.

None of these fixes should affect ABI compatibility; jbig.h remains unchanged.

All past releases of jbig.c are believed to be affected.

The jbig85.c lightwight implementation was not affected.

---

 libjbig/jbig.c     |   16 ++++++++++------

 libjbig/tstcodec.c |   11 ++++++++---

 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/libjbig/jbig.c b/libjbig/jbig.c

index f3c35cc..48fc128 100644

--- a/libjbig/jbig.c

+++ b/libjbig/jbig.c

@@ -1738,7 +1738,7 @@ void jbg_int2dppriv(unsigned char *dptable, const char *internal)

 #define FILL_TABLE1(offset, len, trans) \

   for (i = 0; i < len; i++) { \

     k = 0; \

-    for (j = 0; j < 8; j++) \

+    for (j = 0; i >> j; j++) \

       k |= ((i >> j) & 1) << trans[j]; \

     dptable[(i + offset) >> 2] |= \

       (internal[k + offset] & 3) << ((3 - (i&3)) << 1); \

@@ -1769,7 +1769,7 @@ void jbg_dppriv2int(char *internal, const unsigned char *dptable)

 #define FILL_TABLE2(offset, len, trans) \

   for (i = 0; i < len; i++) { \

     k = 0; \

-    for (j = 0; j < 8; j++) \

+    for (j = 0; i >> j; j++) \

       k |= ((i >> j) & 1) << trans[j]; \

     internal[k + offset] = \

       (dptable[(i + offset) >> 2] >> ((3 - (i & 3)) << 1)) & 3; \

@@ -2574,6 +2574,7 @@ int jbg_dec_in(struct jbg_dec_state *s, unsigned char *data, size_t len,

   unsigned long x, y;

   unsigned long is[3], ie[3];

   size_t dummy_cnt;

+  unsigned char *dppriv;

   if (!cnt) cnt = &dummy_cnt;

   *cnt = 0;

@@ -2711,13 +2712,16 @@ int jbg_dec_in(struct jbg_dec_state *s, unsigned char *data, size_t len,

       (s->options & (JBG_DPON | JBG_DPPRIV | JBG_DPLAST)) ==

       (JBG_DPON | JBG_DPPRIV)) {

     assert(s->bie_len >= 20);

+    if (!s->dppriv || s->dppriv == jbg_dptable)

+      s->dppriv = (char *) checked_malloc(1728, sizeof(char));

     while (s->bie_len < 20 + 1728 && *cnt < len)

-      s->buffer[s->bie_len++ - 20] = data[(*cnt)++];

+      s->dppriv[s->bie_len++ - 20] = data[(*cnt)++];

     if (s->bie_len < 20 + 1728) 

       return JBG_EAGAIN;

-    if (!s->dppriv || s->dppriv == jbg_dptable)

-      s->dppriv = (char *) checked_malloc(1728, sizeof(char));

-    jbg_dppriv2int(s->dppriv, s->buffer);

+    dppriv = s->dppriv;

+    s->dppriv = (char *) checked_malloc(6912, sizeof(char));

+    jbg_dppriv2int(s->dppriv, dppriv);

+    checked_free(dppriv);

   }

   /*

diff --git a/libjbig/tstcodec.c b/libjbig/tstcodec.c

index 44bae57..6289748 100644

--- a/libjbig/tstcodec.c

+++ b/libjbig/tstcodec.c

@@ -483,11 +483,16 @@ int main(int argc, char **argv)

   problems += test_cycle(&pp, 1960, 1951,

 			 JBG_DELAY_AT | JBG_TPBON | JBG_TPDON | JBG_DPON,

 			 0, 6, 1, 2, 8, 279314L, "3.4");

-#if 0

-  puts("Test 3.5: as Test 3.4 but with order bit SEQ set");

+  puts("Test 3.5: as Test 3.4 but with DPPRIV=1");

+  problems += test_cycle(&pp, 1960, 1951,

+			 JBG_DELAY_AT | JBG_TPBON | JBG_TPDON | JBG_DPON |

+			 JBG_DPPRIV,

+			 0, 6, 1, 2, 8, 279314L + 1728, "3.5");

+#if 0 /* Note: option SEQ is currently not supported by the decoder */

+  puts("Test 3.6: as Test 3.4 but with order bit SEQ set");

   problems += test_cycle(&pp, 1960, 1951,

 			 JBG_DELAY_AT | JBG_TPBON | JBG_TPDON | JBG_DPON,

-			 JBG_SEQ, 6, 1, 2, 8, 279314L, "3.5");

+			 JBG_SEQ, 6, 1, 2, 8, 279314L, "3.6");

 #endif

 #endif

-- 

1.7.9.5