aboutsummaryrefslogtreecommitdiffstats
path: root/main/unzip/CVE-2019-13232.patch
blob: 01e343a356f71d428da06735c23ca37def5a0ac8 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
From 47b3ceae397d21bf822bc2ac73052a4b1daf8e1c Mon Sep 17 00:00:00 2001
From: Mark Adler <madler@alumni.caltech.edu>
Date: Tue, 11 Jun 2019 22:01:18 -0700
Subject: [PATCH] Detect and reject a zip bomb using overlapped entries.

This detects an invalid zip file that has at least one entry that
overlaps with another entry or with the central directory to the
end of the file. A Fifield zip bomb uses overlapped local entries
to vastly increase the potential inflation ratio. Such an invalid
zip file is rejected.

See https://www.bamsoftware.com/hacks/zipbomb/ for David Fifield's
analysis, construction, and examples of such zip bombs.

The detection maintains a list of covered spans of the zip files
so far, where the central directory to the end of the file and any
bytes preceding the first entry at zip file offset zero are
considered covered initially. Then as each entry is decompressed
or tested, it is considered covered. When a new entry is about to
be processed, its initial offset is checked to see if it is
contained by a covered span. If so, the zip file is rejected as
invalid.

This commit depends on a preceding commit: "Fix bug in
undefer_input() that misplaced the input state."
---
 extract.c | 190 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 globals.c |   1 +
 globals.h |   3 +
 process.c |  11 ++++
 unzip.h   |   1 +
 5 files changed, 205 insertions(+), 1 deletion(-)

diff --git a/extract.c b/extract.c
index 1acd769..0973a33 100644
--- a/extract.c
+++ b/extract.c
@@ -319,6 +319,125 @@ static ZCONST char Far UnsupportedExtraField[] =
   "\nerror:  unsupported extra-field compression type (%u)--skipping\n";
 static ZCONST char Far BadExtraFieldCRC[] =
   "error [%s]:  bad extra-field CRC %08lx (should be %08lx)\n";
+static ZCONST char Far NotEnoughMemCover[] =
+  "error: not enough memory for bomb detection\n";
+static ZCONST char Far OverlappedComponents[] =
+  "error: invalid zip file with overlapped components (possible zip bomb)\n";
+
+
+
+
+
+/* A growable list of spans. */
+typedef zoff_t bound_t;
+typedef struct {
+    bound_t beg;        /* start of the span */
+    bound_t end;        /* one past the end of the span */
+} span_t;
+typedef struct {
+    span_t *span;       /* allocated, distinct, and sorted list of spans */
+    size_t num;         /* number of spans in the list */
+    size_t max;         /* allocated number of spans (num <= max) */
+} cover_t;
+
+/*
+ * Return the index of the first span in cover whose beg is greater than val.
+ * If there is no such span, then cover->num is returned.
+ */
+static size_t cover_find(cover, val)
+    cover_t *cover;
+    bound_t val;
+{
+    size_t lo = 0, hi = cover->num;
+    while (lo < hi) {
+        size_t mid = (lo + hi) >> 1;
+        if (val < cover->span[mid].beg)
+            hi = mid;
+        else
+            lo = mid + 1;
+    }
+    return hi;
+}
+
+/* Return true if val lies within any one of the spans in cover. */
+static int cover_within(cover, val)
+    cover_t *cover;
+    bound_t val;
+{
+    size_t pos = cover_find(cover, val);
+    return pos > 0 && val < cover->span[pos - 1].end;
+}
+
+/*
+ * Add a new span to the list, but only if the new span does not overlap any
+ * spans already in the list. The new span covers the values beg..end-1. beg
+ * must be less than end.
+ *
+ * Keep the list sorted and merge adjacent spans. Grow the allocated space for
+ * the list as needed. On success, 0 is returned. If the new span overlaps any
+ * existing spans, then 1 is returned and the new span is not added to the
+ * list. If the new span is invalid because beg is greater than or equal to
+ * end, then -1 is returned. If the list needs to be grown but the memory
+ * allocation fails, then -2 is returned.
+ */
+static int cover_add(cover, beg, end)
+    cover_t *cover;
+    bound_t beg;
+    bound_t end;
+{
+    size_t pos;
+    int prec, foll;
+
+    if (beg >= end)
+    /* The new span is invalid. */
+        return -1;
+
+    /* Find where the new span should go, and make sure that it does not
+       overlap with any existing spans. */
+    pos = cover_find(cover, beg);
+    if ((pos > 0 && beg < cover->span[pos - 1].end) ||
+        (pos < cover->num && end > cover->span[pos].beg))
+        return 1;
+
+    /* Check for adjacencies. */
+    prec = pos > 0 && beg == cover->span[pos - 1].end;
+    foll = pos < cover->num && end == cover->span[pos].beg;
+    if (prec && foll) {
+        /* The new span connects the preceding and following spans. Merge the
+           following span into the preceding span, and delete the following
+           span. */
+        cover->span[pos - 1].end = cover->span[pos].end;
+        cover->num--;
+        memmove(cover->span + pos, cover->span + pos + 1,
+                (cover->num - pos) * sizeof(span_t));
+    }
+    else if (prec)
+        /* The new span is adjacent only to the preceding span. Extend the end
+           of the preceding span. */
+        cover->span[pos - 1].end = end;
+    else if (foll)
+        /* The new span is adjacent only to the following span. Extend the
+           beginning of the following span. */
+        cover->span[pos].beg = beg;
+    else {
+        /* The new span has gaps between both the preceding and the following
+           spans. Assure that there is room and insert the span.  */
+        if (cover->num == cover->max) {
+            size_t max = cover->max == 0 ? 16 : cover->max << 1;
+            span_t *span = realloc(cover->span, max * sizeof(span_t));
+            if (span == NULL)
+                return -2;
+            cover->span = span;
+            cover->max = max;
+        }
+        memmove(cover->span + pos + 1, cover->span + pos,
+                (cover->num - pos) * sizeof(span_t));
+        cover->num++;
+        cover->span[pos].beg = beg;
+        cover->span[pos].end = end;
+    }
+    return 0;
+}
 
 
 
@@ -374,6 +493,29 @@ int extract_or_test_files(__G)    /* return PK-type error code */
     }
 #endif /* !SFX || SFX_EXDIR */
 
+    /* One more: initialize cover structure for bomb detection. Start with a
+       span that covers the central directory though the end of the file. */
+    if (G.cover == NULL) {
+        G.cover = malloc(sizeof(cover_t));
+        if (G.cover == NULL) {
+            Info(slide, 0x401, ((char *)slide,
+              LoadFarString(NotEnoughMemCover)));
+            return PK_MEM;
+        }
+        ((cover_t *)G.cover)->span = NULL;
+        ((cover_t *)G.cover)->max = 0;
+    }
+    ((cover_t *)G.cover)->num = 0;
+    if ((G.extra_bytes != 0 &&
+         cover_add((cover_t *)G.cover, 0, G.extra_bytes) != 0) ||
+        cover_add((cover_t *)G.cover,
+                  G.extra_bytes + G.ecrec.offset_start_central_directory,
+                  G.ziplen) != 0) {
+        Info(slide, 0x401, ((char *)slide,
+          LoadFarString(NotEnoughMemCover)));
+        return PK_MEM;
+    }
+
 /*---------------------------------------------------------------------------
     The basic idea of this function is as follows.  Since the central di-
     rectory lies at the end of the zipfile and the member files lie at the
@@ -591,7 +733,8 @@ int extract_or_test_files(__G)    /* return PK-type error code */
             if (error > error_in_archive)
                 error_in_archive = error;
             /* ...and keep going (unless disk full or user break) */
-            if (G.disk_full > 1 || error_in_archive == IZ_CTRLC) {
+            if (G.disk_full > 1 || error_in_archive == IZ_CTRLC ||
+                error == PK_BOMB) {
                 /* clear reached_end to signal premature stop ... */
                 reached_end = FALSE;
                 /* ... and cancel scanning the central directory */
@@ -1060,6 +1203,11 @@ static int extract_or_test_entrylist(__G__ numchunk,
 
         /* seek_zipf(__G__ pInfo->offset);  */
         request = G.pInfo->offset + G.extra_bytes;
+        if (cover_within((cover_t *)G.cover, request)) {
+            Info(slide, 0x401, ((char *)slide,
+              LoadFarString(OverlappedComponents)));
+            return PK_BOMB;
+        }
         inbuf_offset = request % INBUFSIZ;
         bufstart = request - inbuf_offset;
 
@@ -1591,6 +1739,18 @@ static int extract_or_test_entrylist(__G__ numchunk,
             return IZ_CTRLC;        /* cancel operation by user request */
         }
 #endif
+        error = cover_add((cover_t *)G.cover, request,
+                          G.cur_zipfile_bufstart + (G.inptr - G.inbuf));
+        if (error < 0) {
+            Info(slide, 0x401, ((char *)slide,
+              LoadFarString(NotEnoughMemCover)));
+            return PK_MEM;
+        }
+        if (error != 0) {
+            Info(slide, 0x401, ((char *)slide,
+              LoadFarString(OverlappedComponents)));
+            return PK_BOMB;
+        }
 #ifdef MACOS  /* MacOS is no preemptive OS, thus call event-handling by hand */
         UserStop();
 #endif
@@ -1992,6 +2152,34 @@ static int extract_or_test_member(__G)    /* return PK-type error code */
     }
 
     undefer_input(__G);
+
+    if ((G.lrec.general_purpose_bit_flag & 8) != 0) {
+        /* skip over data descriptor (harder than it sounds, due to signature
+         * ambiguity)
+         */
+#       define SIG 0x08074b50
+#       define LOW 0xffffffff
+        uch buf[12];
+        unsigned shy = 12 - readbuf((char *)buf, 12);
+        ulg crc = shy ? 0 : makelong(buf);
+        ulg clen = shy ? 0 : makelong(buf + 4);
+        ulg ulen = shy ? 0 : makelong(buf + 8); /* or high clen if ZIP64 */
+        if (crc == SIG &&                       /* if not SIG, no signature */
+            (G.lrec.crc32 != SIG ||             /* if not SIG, have signature */
+             (clen == SIG &&                    /* if not SIG, no signature */
+              ((G.lrec.csize & LOW) != SIG ||   /* if not SIG, have signature */
+               (ulen == SIG &&                  /* if not SIG, no signature */
+                (G.zip64 ? G.lrec.csize >> 32 : G.lrec.ucsize) != SIG
+                                                /* if not SIG, have signature */
+                )))))
+                   /* skip four more bytes to account for signature */
+                   shy += 4 - readbuf((char *)buf, 4);
+        if (G.zip64)
+            shy += 8 - readbuf((char *)buf, 8); /* skip eight more for ZIP64 */
+        if (shy)
+            error = PK_ERR;
+    }
+
     return error;
 
 } /* end function extract_or_test_member() */
diff --git a/globals.c b/globals.c
index fa8cca5..1e0f608 100644
--- a/globals.c
+++ b/globals.c
@@ -181,6 +181,7 @@ Uz_Globs *globalsCtor()
 # if (!defined(NO_TIMESTAMPS))
     uO.D_flag=1;    /* default to '-D', no restoration of dir timestamps */
 # endif
+    G.cover = NULL;     /* not allocated yet */
 #endif
 
     uO.lflag=(-1);
diff --git a/globals.h b/globals.h
index 11b7215..2bdcdeb 100644
--- a/globals.h
+++ b/globals.h
@@ -260,12 +260,15 @@ typedef struct Globals {
     ecdir_rec       ecrec;         /* used in unzip.c, extract.c */
     z_stat   statbuf;              /* used by main, mapname, check_for_newer */
 
+    int zip64;                     /* true if Zip64 info in extra field */
+
     int      mem_mode;
     uch      *outbufptr;           /* extract.c static */
     ulg      outsize;              /* extract.c static */
     int      reported_backslash;   /* extract.c static */
     int      disk_full;
     int      newfile;
+    void     **cover;              /* used in extract.c for bomb detection */
 
     int      didCRlast;            /* fileio static */
     ulg      numlines;             /* fileio static: number of lines printed */
diff --git a/process.c b/process.c
index 1e9a1e1..d2e4dc3 100644
--- a/process.c
+++ b/process.c
@@ -637,6 +637,13 @@ void free_G_buffers(__G)     /* releases all memory allocated in global vars */
     }
 #endif
 
+    /* Free the cover span list and the cover structure. */
+    if (G.cover != NULL) {
+        free(*(G.cover));
+        free(G.cover);
+        G.cover = NULL;
+    }
+
 } /* end function free_G_buffers() */
 
 
@@ -1890,6 +1897,8 @@ int getZip64Data(__G__ ef_buf, ef_len)
 #define Z64FLGS 0xffff
 #define Z64FLGL 0xffffffff
 
+    G.zip64 = FALSE;
+
     if (ef_len == 0 || ef_buf == NULL)
         return PK_COOL;
 
@@ -1927,6 +1936,8 @@ int getZip64Data(__G__ ef_buf, ef_len)
 #if 0
           break;                /* Expect only one EF_PKSZ64 block. */
 #endif /* 0 */
+
+          G.zip64 = TRUE;
         }

         /* Skip this extra field block. */
diff --git a/unzip.h b/unzip.h
index 5b2a326..ed24a5b 100644
--- a/unzip.h
+++ b/unzip.h
@@ -645,6 +645,7 @@ typedef struct _Uzp_cdir_Rec {
 #define PK_NOZIP           9   /* zipfile not found */
 #define PK_PARAM          10   /* bad or illegal parameters specified */
 #define PK_FIND           11   /* no files found */
+#define PK_BOMB           12   /* likely zip bomb */
 #define PK_DISK           50   /* disk full */
 #define PK_EOF            51   /* unexpected EOF */
 
From 6d351831be705cc26d897db44f878a978f4138fc Mon Sep 17 00:00:00 2001
From: Mark Adler <madler@alumni.caltech.edu>
Date: Thu, 25 Jul 2019 20:43:17 -0700
Subject: [PATCH] Do not raise a zip bomb alert for a misplaced central
 directory.

There is a zip-like file in the Firefox distribution, omni.ja,
which is a zip container with the central directory placed at the
start of the file instead of after the local entries as required
by the zip standard. This commit marks the actual location of the
central directory, as well as the end of central directory records,
as disallowed locations. This now permits such containers to not
raise a zip bomb alert, where in fact there are no overlaps.
---
 extract.c | 25 +++++++++++++++++++------
 process.c |  6 ++++++
 unzpriv.h | 10 ++++++++++
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/extract.c b/extract.c
index 0973a33..1b73cb0 100644
--- a/extract.c
+++ b/extract.c
@@ -493,8 +493,11 @@ int extract_or_test_files(__G)    /* return PK-type error code */
     }
 #endif /* !SFX || SFX_EXDIR */
 
-    /* One more: initialize cover structure for bomb detection. Start with a
-       span that covers the central directory though the end of the file. */
+    /* One more: initialize cover structure for bomb detection. Start with
+       spans that cover any extra bytes at the start, the central directory,
+       the end of central directory record (including the Zip64 end of central
+       directory locator, if present), and the Zip64 end of central directory
+       record, if present. */
     if (G.cover == NULL) {
         G.cover = malloc(sizeof(cover_t));
         if (G.cover == NULL) {
@@ -506,15 +509,25 @@ int extract_or_test_files(__G)    /* return PK-type error code */
         ((cover_t *)G.cover)->max = 0;
     }
     ((cover_t *)G.cover)->num = 0;
-    if ((G.extra_bytes != 0 &&
-         cover_add((cover_t *)G.cover, 0, G.extra_bytes) != 0) ||
-        cover_add((cover_t *)G.cover,
+    if (cover_add((cover_t *)G.cover,
                   G.extra_bytes + G.ecrec.offset_start_central_directory,
-                  G.ziplen) != 0) {
+                  G.extra_bytes + G.ecrec.offset_start_central_directory +
+                  G.ecrec.size_central_directory) != 0) {
         Info(slide, 0x401, ((char *)slide,
           LoadFarString(NotEnoughMemCover)));
         return PK_MEM;
     }
+    if ((G.extra_bytes != 0 &&
+         cover_add((cover_t *)G.cover, 0, G.extra_bytes) != 0) ||
+        (G.ecrec.have_ecr64 &&
+         cover_add((cover_t *)G.cover, G.ecrec.ec64_start,
+                   G.ecrec.ec64_end) != 0) ||
+        cover_add((cover_t *)G.cover, G.ecrec.ec_start,
+                  G.ecrec.ec_end) != 0) {
+        Info(slide, 0x401, ((char *)slide,
+          LoadFarString(OverlappedComponents)));
+        return PK_BOMB;
+    }
 
 /*---------------------------------------------------------------------------
     The basic idea of this function is as follows.  Since the central di-
diff --git a/process.c b/process.c
index d2e4dc3..d75d405 100644
--- a/process.c
+++ b/process.c
@@ -1408,6 +1408,10 @@ static int find_ecrec64(__G__ searchlen)         /* return PK-class error */
 
     /* Now, we are (almost) sure that we have a Zip64 archive. */
     G.ecrec.have_ecr64 = 1;
+    G.ecrec.ec_start -= ECLOC64_SIZE+4;
+    G.ecrec.ec64_start = ecrec64_start_offset;
+    G.ecrec.ec64_end = ecrec64_start_offset +
+                       12 + makeint64(&byterec[ECREC64_LENGTH]);
 
     /* Update the "end-of-central-dir offset" for later checks. */
     G.real_ecrec_offset = ecrec64_start_offset;
@@ -1542,6 +1546,8 @@ static int find_ecrec(__G__ searchlen)          /* return PK-class error */
       makelong(&byterec[OFFSET_START_CENTRAL_DIRECTORY]);
     G.ecrec.zipfile_comment_length =
       makeword(&byterec[ZIPFILE_COMMENT_LENGTH]);
+    G.ecrec.ec_start = G.real_ecrec_offset;
+    G.ecrec.ec_end = G.ecrec.ec_start + 22 + G.ecrec.zipfile_comment_length;
 
     /* Now, we have to read the archive comment, BEFORE the file pointer
        is moved away backwards to seek for a Zip64 ECLOC64 structure.
diff --git a/unzpriv.h b/unzpriv.h
index dc9eff5..297b3c7 100644
--- a/unzpriv.h
+++ b/unzpriv.h
@@ -2185,6 +2185,16 @@ typedef struct VMStimbuf {
        int have_ecr64;                  /* valid Zip64 ecdir-record exists */
        int is_zip64_archive;            /* Zip64 ecdir-record is mandatory */
        ush zipfile_comment_length;
+       zusz_t ec_start, ec_end;         /* offsets of start and end of the
+                                           end of central directory record,
+                                           including if present the Zip64
+                                           end of central directory locator,
+                                           which immediately precedes the
+                                           end of central directory record */
+       zusz_t ec64_start, ec64_end;     /* if have_ecr64 is true, then these
+                                           are the offsets of the start and
+                                           end of the Zip64 end of central
+                                           directory record */
    } ecdir_rec;
 
 
From 41beb477c5744bc396fa1162ee0c14218ec12213 Mon Sep 17 00:00:00 2001
From: Mark Adler <madler@alumni.caltech.edu>
Date: Mon, 27 May 2019 08:20:32 -0700
Subject: [PATCH] Fix bug in undefer_input() that misplaced the input state.

---
 fileio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fileio.c b/fileio.c
index c042987..bc00d74 100644
--- a/fileio.c
+++ b/fileio.c
@@ -530,8 +530,10 @@ void undefer_input(__G)
          * This condition was checked when G.incnt_leftover was set > 0 in
          * defer_leftover_input(), and it is NOT allowed to touch G.csize
          * before calling undefer_input() when (G.incnt_leftover > 0)
-         * (single exception: see read_byte()'s  "G.csize <= 0" handling) !!
+         * (single exception: see readbyte()'s  "G.csize <= 0" handling) !!
          */
+        if (G.csize < 0L)
+            G.csize = 0L;
         G.incnt = G.incnt_leftover + (int)G.csize;
         G.inptr = G.inptr_leftover - (int)G.csize;
         G.incnt_leftover = 0;