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From a9bfab5b52d08879bbc5e0991684b700127ddcff Mon Sep 17 00:00:00 2001
From: mancha <mancha1 AT zoho DOT com>
Date: Mon, 3 Nov 2014
Subject: Info-ZIP UnZip buffer overflow
By carefully crafting a corrupt ZIP archive with "extra fields" that
purport to have compressed blocks larger than the corresponding
uncompressed blocks in STORED no-compression mode, an attacker can
trigger a heap overflow that can result in application crash or
possibly have other unspecified impact.
This patch ensures that when extra fields use STORED mode, the
"compressed" and uncompressed block sizes match.
---
extract.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/extract.c
+++ b/extract.c
@@ -2217,6 +2217,7 @@ static int test_compr_eb(__G__ eb, eb_si
ulg eb_ucsize;
uch *eb_ucptr;
int r;
+ ush method;
if (compr_offset < 4) /* field is not compressed: */
return PK_OK; /* do nothing and signal OK */
@@ -2226,6 +2227,12 @@ static int test_compr_eb(__G__ eb, eb_si
eb_size <= (compr_offset + EB_CMPRHEADLEN)))
return IZ_EF_TRUNC; /* no compressed data! */
+ method = makeword(eb + (EB_HEADSIZE + compr_offset));
+ if ((method == STORED) && (eb_size - compr_offset != eb_ucsize))
+ return PK_ERR; /* compressed & uncompressed
+ * should match in STORED
+ * method */
+
if (
#ifdef INT_16BIT
(((ulg)(extent)eb_ucsize) != eb_ucsize) ||
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