diff options
Diffstat (limited to 'tools/zlib/patches/006-fix-compressor-crash-on-certain-inputs.patch')
| -rw-r--r-- | tools/zlib/patches/006-fix-compressor-crash-on-certain-inputs.patch | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/tools/zlib/patches/006-fix-compressor-crash-on-certain-inputs.patch b/tools/zlib/patches/006-fix-compressor-crash-on-certain-inputs.patch new file mode 100644 index 0000000000..9f37ba5c58 --- /dev/null +++ b/tools/zlib/patches/006-fix-compressor-crash-on-certain-inputs.patch @@ -0,0 +1,343 @@ +From 5c44459c3b28a9bd3283aaceab7c615f8020c531 Mon Sep 17 00:00:00 2001 +From: Mark Adler <madler@alumni.caltech.edu> +Date: Tue, 17 Apr 2018 22:09:22 -0700 +Subject: [PATCH] Fix a bug that can crash deflate on some input when using + Z_FIXED. + +This bug was reported by Danilo Ramos of Eideticom, Inc. It has +lain in wait 13 years before being found! The bug was introduced +in zlib 1.2.2.2, with the addition of the Z_FIXED option. That +option forces the use of fixed Huffman codes. For rare inputs with +a large number of distant matches, the pending buffer into which +the compressed data is written can overwrite the distance symbol +table which it overlays. That results in corrupted output due to +invalid distances, and can result in out-of-bound accesses, +crashing the application. + +The fix here combines the distance buffer and literal/length +buffers into a single symbol buffer. Now three bytes of pending +buffer space are opened up for each literal or length/distance +pair consumed, instead of the previous two bytes. This assures +that the pending buffer cannot overwrite the symbol table, since +the maximum fixed code compressed length/distance is 31 bits, and +since there are four bytes of pending space for every three bytes +of symbol space. +--- + deflate.c | 74 ++++++++++++++++++++++++++++++++++++++++--------------- + deflate.h | 25 +++++++++---------- + trees.c | 50 +++++++++++-------------------------- + 3 files changed, 79 insertions(+), 70 deletions(-) + +diff --git a/deflate.c b/deflate.c +index 425babc00..19cba873a 100644 +--- a/deflate.c ++++ b/deflate.c +@@ -255,11 +255,6 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, + int wrap = 1; + static const char my_version[] = ZLIB_VERSION; + +- ushf *overlay; +- /* We overlay pending_buf and d_buf+l_buf. This works since the average +- * output size for (length,distance) codes is <= 24 bits. +- */ +- + if (version == Z_NULL || version[0] != my_version[0] || + stream_size != sizeof(z_stream)) { + return Z_VERSION_ERROR; +@@ -329,9 +324,47 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, + + s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ + +- overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); +- s->pending_buf = (uchf *) overlay; +- s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); ++ /* We overlay pending_buf and sym_buf. This works since the average size ++ * for length/distance pairs over any compressed block is assured to be 31 ++ * bits or less. ++ * ++ * Analysis: The longest fixed codes are a length code of 8 bits plus 5 ++ * extra bits, for lengths 131 to 257. The longest fixed distance codes are ++ * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest ++ * possible fixed-codes length/distance pair is then 31 bits total. ++ * ++ * sym_buf starts one-fourth of the way into pending_buf. So there are ++ * three bytes in sym_buf for every four bytes in pending_buf. Each symbol ++ * in sym_buf is three bytes -- two for the distance and one for the ++ * literal/length. As each symbol is consumed, the pointer to the next ++ * sym_buf value to read moves forward three bytes. From that symbol, up to ++ * 31 bits are written to pending_buf. The closest the written pending_buf ++ * bits gets to the next sym_buf symbol to read is just before the last ++ * code is written. At that time, 31*(n-2) bits have been written, just ++ * after 24*(n-2) bits have been consumed from sym_buf. sym_buf starts at ++ * 8*n bits into pending_buf. (Note that the symbol buffer fills when n-1 ++ * symbols are written.) The closest the writing gets to what is unread is ++ * then n+14 bits. Here n is lit_bufsize, which is 16384 by default, and ++ * can range from 128 to 32768. ++ * ++ * Therefore, at a minimum, there are 142 bits of space between what is ++ * written and what is read in the overlain buffers, so the symbols cannot ++ * be overwritten by the compressed data. That space is actually 139 bits, ++ * due to the three-bit fixed-code block header. ++ * ++ * That covers the case where either Z_FIXED is specified, forcing fixed ++ * codes, or when the use of fixed codes is chosen, because that choice ++ * results in a smaller compressed block than dynamic codes. That latter ++ * condition then assures that the above analysis also covers all dynamic ++ * blocks. A dynamic-code block will only be chosen to be emitted if it has ++ * fewer bits than a fixed-code block would for the same set of symbols. ++ * Therefore its average symbol length is assured to be less than 31. So ++ * the compressed data for a dynamic block also cannot overwrite the ++ * symbols from which it is being constructed. ++ */ ++ ++ s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4); ++ s->pending_buf_size = (ulg)s->lit_bufsize * 4; + + if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || + s->pending_buf == Z_NULL) { +@@ -340,8 +373,12 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, + deflateEnd (strm); + return Z_MEM_ERROR; + } +- s->d_buf = overlay + s->lit_bufsize/sizeof(ush); +- s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; ++ s->sym_buf = s->pending_buf + s->lit_bufsize; ++ s->sym_end = (s->lit_bufsize - 1) * 3; ++ /* We avoid equality with lit_bufsize*3 because of wraparound at 64K ++ * on 16 bit machines and because stored blocks are restricted to ++ * 64K-1 bytes. ++ */ + + s->level = level; + s->strategy = strategy; +@@ -552,7 +589,7 @@ int ZEXPORT deflatePrime (strm, bits, value) + + if (deflateStateCheck(strm)) return Z_STREAM_ERROR; + s = strm->state; +- if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3)) ++ if (s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) + return Z_BUF_ERROR; + do { + put = Buf_size - s->bi_valid; +@@ -1113,7 +1150,6 @@ int ZEXPORT deflateCopy (dest, source) + #else + deflate_state *ds; + deflate_state *ss; +- ushf *overlay; + + + if (deflateStateCheck(source) || dest == Z_NULL) { +@@ -1133,8 +1169,7 @@ int ZEXPORT deflateCopy (dest, source) + ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); + ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); + ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); +- overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); +- ds->pending_buf = (uchf *) overlay; ++ ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4); + + if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || + ds->pending_buf == Z_NULL) { +@@ -1148,8 +1183,7 @@ int ZEXPORT deflateCopy (dest, source) + zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); + + ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); +- ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); +- ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; ++ ds->sym_buf = ds->pending_buf + ds->lit_bufsize; + + ds->l_desc.dyn_tree = ds->dyn_ltree; + ds->d_desc.dyn_tree = ds->dyn_dtree; +@@ -1925,7 +1959,7 @@ local block_state deflate_fast(s, flush) + FLUSH_BLOCK(s, 1); + return finish_done; + } +- if (s->last_lit) ++ if (s->sym_next) + FLUSH_BLOCK(s, 0); + return block_done; + } +@@ -2056,7 +2090,7 @@ local block_state deflate_slow(s, flush) + FLUSH_BLOCK(s, 1); + return finish_done; + } +- if (s->last_lit) ++ if (s->sym_next) + FLUSH_BLOCK(s, 0); + return block_done; + } +@@ -2131,7 +2165,7 @@ local block_state deflate_rle(s, flush) + FLUSH_BLOCK(s, 1); + return finish_done; + } +- if (s->last_lit) ++ if (s->sym_next) + FLUSH_BLOCK(s, 0); + return block_done; + } +@@ -2170,7 +2204,7 @@ local block_state deflate_huff(s, flush) + FLUSH_BLOCK(s, 1); + return finish_done; + } +- if (s->last_lit) ++ if (s->sym_next) + FLUSH_BLOCK(s, 0); + return block_done; + } +diff --git a/deflate.h b/deflate.h +index 23ecdd312..d4cf1a98b 100644 +--- a/deflate.h ++++ b/deflate.h +@@ -217,7 +217,7 @@ 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 +@@ -239,13 +239,8 @@ 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 */ +@@ -325,20 +320,22 @@ 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 = (uch)(length); \ + ush dist = (ush)(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) +diff --git a/trees.c b/trees.c +index 4f4a65011..decaeb7c3 100644 +--- a/trees.c ++++ b/trees.c +@@ -416,7 +416,7 @@ local void init_block(s) + + s->dyn_ltree[END_BLOCK].Freq = 1; + s->opt_len = s->static_len = 0L; +- s->last_lit = s->matches = 0; ++ s->sym_next = s->matches = 0; + } + + #define SMALLEST 1 +@@ -948,7 +948,7 @@ void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last) + + Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", + opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, +- s->last_lit)); ++ s->sym_next / 3)); + + if (static_lenb <= opt_lenb) opt_lenb = static_lenb; + +@@ -1017,8 +1017,9 @@ int ZLIB_INTERNAL _tr_tally (s, dist, lc) + unsigned dist; /* distance of matched string */ + unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ + { +- s->d_buf[s->last_lit] = (ush)dist; +- s->l_buf[s->last_lit++] = (uch)lc; ++ s->sym_buf[s->sym_next++] = dist; ++ s->sym_buf[s->sym_next++] = dist >> 8; ++ s->sym_buf[s->sym_next++] = lc; + if (dist == 0) { + /* lc is the unmatched char */ + s->dyn_ltree[lc].Freq++; +@@ -1033,30 +1034,7 @@ int ZLIB_INTERNAL _tr_tally (s, dist, lc) + s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; + s->dyn_dtree[d_code(dist)].Freq++; + } +- +-#ifdef TRUNCATE_BLOCK +- /* Try to guess if it is profitable to stop the current block here */ +- if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { +- /* Compute an upper bound for the compressed length */ +- ulg out_length = (ulg)s->last_lit*8L; +- ulg in_length = (ulg)((long)s->strstart - s->block_start); +- int dcode; +- for (dcode = 0; dcode < D_CODES; dcode++) { +- out_length += (ulg)s->dyn_dtree[dcode].Freq * +- (5L+extra_dbits[dcode]); +- } +- out_length >>= 3; +- Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", +- s->last_lit, in_length, out_length, +- 100L - out_length*100L/in_length)); +- if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; +- } +-#endif +- return (s->last_lit == s->lit_bufsize-1); +- /* We avoid equality with lit_bufsize because of wraparound at 64K +- * on 16 bit machines and because stored blocks are restricted to +- * 64K-1 bytes. +- */ ++ return (s->sym_next == s->sym_end); + } + + /* =========================================================================== +@@ -1069,13 +1047,14 @@ local void compress_block(s, ltree, dtree) + { + unsigned dist; /* distance of matched string */ + int lc; /* match length or unmatched char (if dist == 0) */ +- unsigned lx = 0; /* running index in l_buf */ ++ unsigned sx = 0; /* running index in sym_buf */ + unsigned code; /* the code to send */ + int extra; /* number of extra bits to send */ + +- if (s->last_lit != 0) do { +- dist = s->d_buf[lx]; +- lc = s->l_buf[lx++]; ++ if (s->sym_next != 0) do { ++ dist = s->sym_buf[sx++] & 0xff; ++ dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8; ++ lc = s->sym_buf[sx++]; + if (dist == 0) { + send_code(s, lc, ltree); /* send a literal byte */ + Tracecv(isgraph(lc), (stderr," '%c' ", lc)); +@@ -1100,11 +1079,10 @@ local void compress_block(s, ltree, dtree) + } + } /* literal or match pair ? */ + +- /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ +- Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx, +- "pendingBuf overflow"); ++ /* Check that the overlay between pending_buf and sym_buf is ok: */ ++ Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow"); + +- } while (lx < s->last_lit); ++ } while (sx < s->sym_next); + + send_code(s, END_BLOCK, ltree); + } |