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+From 1aae47fa8935654a84403768f32c03ecbb1be470 Mon Sep 17 00:00:00 2001
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+From: Mark Adler <madler@alumni.caltech.edu>
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+Date: Tue, 11 Jun 2019 22:01:18 -0700
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+Subject: [PATCH 2/3] Detect and reject a zip bomb using overlapped entries.
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+
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+This detects an invalid zip file that has at least one entry that
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+overlaps with another entry or with the central directory to the
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+end of the file. A Fifield zip bomb uses overlapped local entries
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+to vastly increase the potential inflation ratio. Such an invalid
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+zip file is rejected.
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+
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+See https://www.bamsoftware.com/hacks/zipbomb/ for David Fifield's
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+analysis, construction, and examples of such zip bombs.
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+
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+The detection maintains a list of covered spans of the zip files
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+so far, where the central directory to the end of the file and any
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+bytes preceding the first entry at zip file offset zero are
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+considered covered initially. Then as each entry is decompressed
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+or tested, it is considered covered. When a new entry is about to
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+be processed, its initial offset is checked to see if it is
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+contained by a covered span. If so, the zip file is rejected as
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+invalid.
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+
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+This commit depends on a preceding commit: "Fix bug in
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+undefer_input() that misplaced the input state."
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+
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+CVE: CVE-2019-13232
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+Upstream-Status: Backport
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+[https://github.com/madler/unzip/commit/47b3ceae397d21bf822bc2ac73052a4b1daf8e1c]
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+
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+Signed-off-by: Dan Tran <dantran@microsoft.com>
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+---
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+ extract.c | 190 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
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+ globals.c | 1 +
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+ globals.h | 3 +
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+ process.c | 10 +++
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+ unzip.h | 1 +
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+ 5 files changed, 204 insertions(+), 1 deletion(-)
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+
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+diff --git a/extract.c b/extract.c
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+index 24db2a8..2bb72ba 100644
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+--- a/extract.c
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++++ b/extract.c
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+@@ -321,6 +321,125 @@ static ZCONST char Far UnsupportedExtraField[] =
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+ "\nerror: unsupported extra-field compression type (%u)--skipping\n";
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+ static ZCONST char Far BadExtraFieldCRC[] =
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+ "error [%s]: bad extra-field CRC %08lx (should be %08lx)\n";
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++static ZCONST char Far NotEnoughMemCover[] =
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++ "error: not enough memory for bomb detection\n";
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++static ZCONST char Far OverlappedComponents[] =
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++ "error: invalid zip file with overlapped components (possible zip bomb)\n";
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++
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++
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++
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++
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++
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++/* A growable list of spans. */
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++typedef zoff_t bound_t;
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++typedef struct {
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++ bound_t beg; /* start of the span */
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++ bound_t end; /* one past the end of the span */
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++} span_t;
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++typedef struct {
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++ span_t *span; /* allocated, distinct, and sorted list of spans */
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++ size_t num; /* number of spans in the list */
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++ size_t max; /* allocated number of spans (num <= max) */
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++} cover_t;
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++
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++/*
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++ * Return the index of the first span in cover whose beg is greater than val.
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++ * If there is no such span, then cover->num is returned.
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++ */
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++static size_t cover_find(cover, val)
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++ cover_t *cover;
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++ bound_t val;
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++{
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++ size_t lo = 0, hi = cover->num;
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++ while (lo < hi) {
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++ size_t mid = (lo + hi) >> 1;
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++ if (val < cover->span[mid].beg)
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++ hi = mid;
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++ else
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++ lo = mid + 1;
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++ }
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++ return hi;
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++}
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++
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++/* Return true if val lies within any one of the spans in cover. */
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++static int cover_within(cover, val)
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++ cover_t *cover;
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++ bound_t val;
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++{
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++ size_t pos = cover_find(cover, val);
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++ return pos > 0 && val < cover->span[pos - 1].end;
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++}
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++
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++/*
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++ * Add a new span to the list, but only if the new span does not overlap any
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++ * spans already in the list. The new span covers the values beg..end-1. beg
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++ * must be less than end.
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++ *
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++ * Keep the list sorted and merge adjacent spans. Grow the allocated space for
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++ * the list as needed. On success, 0 is returned. If the new span overlaps any
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++ * existing spans, then 1 is returned and the new span is not added to the
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++ * list. If the new span is invalid because beg is greater than or equal to
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++ * end, then -1 is returned. If the list needs to be grown but the memory
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++ * allocation fails, then -2 is returned.
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++ */
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++static int cover_add(cover, beg, end)
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++ cover_t *cover;
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++ bound_t beg;
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++ bound_t end;
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++{
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++ size_t pos;
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++ int prec, foll;
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++
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++ if (beg >= end)
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++ /* The new span is invalid. */
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++ return -1;
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++
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++ /* Find where the new span should go, and make sure that it does not
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++ overlap with any existing spans. */
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++ pos = cover_find(cover, beg);
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++ if ((pos > 0 && beg < cover->span[pos - 1].end) ||
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++ (pos < cover->num && end > cover->span[pos].beg))
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++ return 1;
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++
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++ /* Check for adjacencies. */
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++ prec = pos > 0 && beg == cover->span[pos - 1].end;
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++ foll = pos < cover->num && end == cover->span[pos].beg;
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++ if (prec && foll) {
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++ /* The new span connects the preceding and following spans. Merge the
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++ following span into the preceding span, and delete the following
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++ span. */
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++ cover->span[pos - 1].end = cover->span[pos].end;
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++ cover->num--;
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++ memmove(cover->span + pos, cover->span + pos + 1,
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++ (cover->num - pos) * sizeof(span_t));
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++ }
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++ else if (prec)
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++ /* The new span is adjacent only to the preceding span. Extend the end
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++ of the preceding span. */
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++ cover->span[pos - 1].end = end;
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++ else if (foll)
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++ /* The new span is adjacent only to the following span. Extend the
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++ beginning of the following span. */
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++ cover->span[pos].beg = beg;
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++ else {
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++ /* The new span has gaps between both the preceding and the following
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++ spans. Assure that there is room and insert the span. */
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++ if (cover->num == cover->max) {
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++ size_t max = cover->max == 0 ? 16 : cover->max << 1;
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++ span_t *span = realloc(cover->span, max * sizeof(span_t));
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++ if (span == NULL)
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++ return -2;
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++ cover->span = span;
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++ cover->max = max;
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++ }
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++ memmove(cover->span + pos + 1, cover->span + pos,
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++ (cover->num - pos) * sizeof(span_t));
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++ cover->num++;
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++ cover->span[pos].beg = beg;
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++ cover->span[pos].end = end;
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++ }
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++ return 0;
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++}
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+
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+
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+
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+@@ -376,6 +495,29 @@ int extract_or_test_files(__G) /* return PK-type error code */
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+ }
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+ #endif /* !SFX || SFX_EXDIR */
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+
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++ /* One more: initialize cover structure for bomb detection. Start with a
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++ span that covers the central directory though the end of the file. */
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++ if (G.cover == NULL) {
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++ G.cover = malloc(sizeof(cover_t));
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++ if (G.cover == NULL) {
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++ Info(slide, 0x401, ((char *)slide,
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++ LoadFarString(NotEnoughMemCover)));
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++ return PK_MEM;
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++ }
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++ ((cover_t *)G.cover)->span = NULL;
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++ ((cover_t *)G.cover)->max = 0;
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++ }
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++ ((cover_t *)G.cover)->num = 0;
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++ if ((G.extra_bytes != 0 &&
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++ cover_add((cover_t *)G.cover, 0, G.extra_bytes) != 0) ||
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++ cover_add((cover_t *)G.cover,
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++ G.extra_bytes + G.ecrec.offset_start_central_directory,
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++ G.ziplen) != 0) {
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++ Info(slide, 0x401, ((char *)slide,
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++ LoadFarString(NotEnoughMemCover)));
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++ return PK_MEM;
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++ }
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++
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+ /*---------------------------------------------------------------------------
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+ The basic idea of this function is as follows. Since the central di-
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+ rectory lies at the end of the zipfile and the member files lie at the
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+@@ -593,7 +735,8 @@ int extract_or_test_files(__G) /* return PK-type error code */
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+ if (error > error_in_archive)
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+ error_in_archive = error;
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+ /* ...and keep going (unless disk full or user break) */
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+- if (G.disk_full > 1 || error_in_archive == IZ_CTRLC) {
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++ if (G.disk_full > 1 || error_in_archive == IZ_CTRLC ||
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++ error == PK_BOMB) {
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+ /* clear reached_end to signal premature stop ... */
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+ reached_end = FALSE;
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+ /* ... and cancel scanning the central directory */
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+@@ -1062,6 +1205,11 @@ static int extract_or_test_entrylist(__G__ numchunk,
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+
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+ /* seek_zipf(__G__ pInfo->offset); */
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+ request = G.pInfo->offset + G.extra_bytes;
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++ if (cover_within((cover_t *)G.cover, request)) {
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++ Info(slide, 0x401, ((char *)slide,
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++ LoadFarString(OverlappedComponents)));
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++ return PK_BOMB;
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++ }
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+ inbuf_offset = request % INBUFSIZ;
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+ bufstart = request - inbuf_offset;
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+
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+@@ -1593,6 +1741,18 @@ reprompt:
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+ return IZ_CTRLC; /* cancel operation by user request */
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+ }
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+ #endif
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++ error = cover_add((cover_t *)G.cover, request,
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++ G.cur_zipfile_bufstart + (G.inptr - G.inbuf));
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++ if (error < 0) {
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++ Info(slide, 0x401, ((char *)slide,
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++ LoadFarString(NotEnoughMemCover)));
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++ return PK_MEM;
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++ }
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++ if (error != 0) {
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++ Info(slide, 0x401, ((char *)slide,
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++ LoadFarString(OverlappedComponents)));
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++ return PK_BOMB;
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++ }
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+ #ifdef MACOS /* MacOS is no preemptive OS, thus call event-handling by hand */
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+ UserStop();
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+ #endif
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+@@ -1994,6 +2154,34 @@ static int extract_or_test_member(__G) /* return PK-type error code */
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+ }
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+
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+ undefer_input(__G);
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++
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++ if ((G.lrec.general_purpose_bit_flag & 8) != 0) {
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++ /* skip over data descriptor (harder than it sounds, due to signature
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++ * ambiguity)
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++ */
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++# define SIG 0x08074b50
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++# define LOW 0xffffffff
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++ uch buf[12];
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++ unsigned shy = 12 - readbuf((char *)buf, 12);
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++ ulg crc = shy ? 0 : makelong(buf);
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++ ulg clen = shy ? 0 : makelong(buf + 4);
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++ ulg ulen = shy ? 0 : makelong(buf + 8); /* or high clen if ZIP64 */
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++ if (crc == SIG && /* if not SIG, no signature */
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++ (G.lrec.crc32 != SIG || /* if not SIG, have signature */
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++ (clen == SIG && /* if not SIG, no signature */
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++ ((G.lrec.csize & LOW) != SIG || /* if not SIG, have signature */
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++ (ulen == SIG && /* if not SIG, no signature */
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++ (G.zip64 ? G.lrec.csize >> 32 : G.lrec.ucsize) != SIG
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++ /* if not SIG, have signature */
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++ )))))
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++ /* skip four more bytes to account for signature */
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++ shy += 4 - readbuf((char *)buf, 4);
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++ if (G.zip64)
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++ shy += 8 - readbuf((char *)buf, 8); /* skip eight more for ZIP64 */
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++ if (shy)
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++ error = PK_ERR;
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++ }
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++
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+ return error;
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+
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+ } /* end function extract_or_test_member() */
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+diff --git a/globals.c b/globals.c
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+index fa8cca5..1e0f608 100644
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+--- a/globals.c
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++++ b/globals.c
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+@@ -181,6 +181,7 @@ Uz_Globs *globalsCtor()
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+ # if (!defined(NO_TIMESTAMPS))
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+ uO.D_flag=1; /* default to '-D', no restoration of dir timestamps */
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+ # endif
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++ G.cover = NULL; /* not allocated yet */
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+ #endif
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+
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+ uO.lflag=(-1);
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+diff --git a/globals.h b/globals.h
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+index 11b7215..2bdcdeb 100644
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+--- a/globals.h
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++++ b/globals.h
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+@@ -260,12 +260,15 @@ typedef struct Globals {
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+ ecdir_rec ecrec; /* used in unzip.c, extract.c */
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+ z_stat statbuf; /* used by main, mapname, check_for_newer */
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+
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++ int zip64; /* true if Zip64 info in extra field */
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++
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+ int mem_mode;
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+ uch *outbufptr; /* extract.c static */
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+ ulg outsize; /* extract.c static */
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+ int reported_backslash; /* extract.c static */
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+ int disk_full;
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+ int newfile;
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++ void **cover; /* used in extract.c for bomb detection */
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+
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+ int didCRlast; /* fileio static */
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+ ulg numlines; /* fileio static: number of lines printed */
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+diff --git a/process.c b/process.c
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+index a3c1a4d..208619c 100644
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+--- a/process.c
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++++ b/process.c
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+@@ -637,6 +637,13 @@ void free_G_buffers(__G) /* releases all memory allocated in global vars */
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+ }
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+ #endif
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+
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++ /* Free the cover span list and the cover structure. */
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++ if (G.cover != NULL) {
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++ free(*(G.cover));
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++ free(G.cover);
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++ G.cover = NULL;
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++ }
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++
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+ } /* end function free_G_buffers() */
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+
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+
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+@@ -1905,6 +1912,7 @@ int getZip64Data(__G__ ef_buf, ef_len)
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+
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+ #define Z64FLGS 0xffff
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+ #define Z64FLGL 0xffffffff
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++ G.zip64 = FALSE;
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+
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+ if (ef_len == 0 || ef_buf == NULL)
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+ return PK_COOL;
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+@@ -1964,6 +1972,8 @@ int getZip64Data(__G__ ef_buf, ef_len)
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+ G.crec.disk_number_start = (zuvl_t)makelong(offset + ef_buf);
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+ offset += 4;
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+ }
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++
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++ G.zip64 = TRUE;
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+ #if 0
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+ break; /* Expect only one EF_PKSZ64 block. */
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+ #endif /* 0 */
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+diff --git a/unzip.h b/unzip.h
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+index 5b2a326..ed24a5b 100644
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+--- a/unzip.h
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++++ b/unzip.h
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+@@ -645,6 +645,7 @@ typedef struct _Uzp_cdir_Rec {
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+ #define PK_NOZIP 9 /* zipfile not found */
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+ #define PK_PARAM 10 /* bad or illegal parameters specified */
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+ #define PK_FIND 11 /* no files found */
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++#define PK_BOMB 12 /* likely zip bomb */
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+ #define PK_DISK 50 /* disk full */
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+ #define PK_EOF 51 /* unexpected EOF */
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+
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+--
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+2.22.0.vfs.1.1.57.gbaf16c8
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