zlib: Port fix for CVE-2018-25032 to U-Boot

While our copy of zlib is missing upstream commit 263b1a05b04e ("Allow
deflatePrime() to insert bits in the middle of a stream.") we do have
Z_FIXED support, and so the majority of the code changes in 5c44459c3b28
("Fix a bug that can crash deflate on some input when using Z_FIXED.")
apply here directly and cleanly.  As this has been assigned a CVE, lets
go and apply these changes.

Link: https://github.com/madler/zlib/commit/5c44459c3b28a9bd3283aaceab7c615f8020c531
Reported-by: "Gan, Yau Wai" <yau.wai.gan@intel.com>
Signed-off-by: Tom Rini <trini@konsulko.com>

1 files changed, 11 insertions, 14 deletions

diff --git a/lib/zlib/deflate.h b/lib/zlib/deflate.h
index cbf0d1ea5d9..4c53b94af0b 100644
--- a/lib/zlib/deflate.h
+++ b/lib/zlib/deflate.h
@@ -211,7 +211,7 @@ typedef struct internal_state {
     /* Depth of each subtree used as tie breaker for trees of equal frequency
      */
 
-    uchf *l_buf;          /* buffer for literals or lengths */
+    uchf *sym_buf;        /* buffer for distances and literals/lengths */
 
     uInt  lit_bufsize;
     /* Size of match buffer for literals/lengths.  There are 4 reasons for
@@ -233,13 +233,8 @@ typedef struct internal_state {
      *   - I can't count above 4
      */
 
-    uInt last_lit;      /* running index in l_buf */
-
-    ushf *d_buf;
-    /* Buffer for distances. To simplify the code, d_buf and l_buf have
-     * the same number of elements. To use different lengths, an extra flag
-     * array would be necessary.
-     */
+    uInt sym_next;      /* running index in sym_buf */
+    uInt sym_end;       /* symbol table full when sym_next reaches this */
 
     ulg opt_len;        /* bit length of current block with optimal trees */
     ulg static_len;     /* bit length of current block with static trees */
@@ -318,20 +313,22 @@ void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf,
 
 # define _tr_tally_lit(s, c, flush) \
   { uch cc = (c); \
-    s->d_buf[s->last_lit] = 0; \
-    s->l_buf[s->last_lit++] = cc; \
+    s->sym_buf[s->sym_next++] = 0; \
+    s->sym_buf[s->sym_next++] = 0; \
+    s->sym_buf[s->sym_next++] = cc; \
     s->dyn_ltree[cc].Freq++; \
-    flush = (s->last_lit == s->lit_bufsize-1); \
+    flush = (s->sym_next == s->sym_end); \
    }
 # define _tr_tally_dist(s, distance, length, flush) \
   { uch len = (length); \
     ush dist = (distance); \
-    s->d_buf[s->last_lit] = dist; \
-    s->l_buf[s->last_lit++] = len; \
+    s->sym_buf[s->sym_next++] = dist; \
+    s->sym_buf[s->sym_next++] = dist >> 8; \
+    s->sym_buf[s->sym_next++] = len; \
     dist--; \
     s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
     s->dyn_dtree[d_code(dist)].Freq++; \
-    flush = (s->last_lit == s->lit_bufsize-1); \
+    flush = (s->sym_next == s->sym_end); \
   }
 #else
 # define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)