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CVE: CVE-2018-1000020
Upstream-Status: Backport
Signed-off-by: Ross Burton <ross.burton@intel.com>
From 8312eaa576014cd9b965012af51bc1f967b12423 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Tue, 1 Jan 2019 17:10:49 +1100
Subject: [PATCH 1/2] iso9660: Fail when expected Rockridge extensions is
missing
A corrupted or malicious ISO9660 image can cause read_CE() to loop
forever.
read_CE() calls parse_rockridge(), expecting a Rockridge extension
to be read. However, parse_rockridge() is structured as a while
loop starting with a sanity check, and if the sanity check fails
before the loop has run, the function returns ARCHIVE_OK without
advancing the position in the file. This causes read_CE() to retry
indefinitely.
Make parse_rockridge() return ARCHIVE_WARN if it didn't read an
extension. As someone with no real knowledge of the format, this
seems more apt than ARCHIVE_FATAL, but both the call-sites escalate
it to a fatal error immediately anyway.
Found with a combination of AFL, afl-rb (FairFuzz) and qsym.
---
libarchive/archive_read_support_format_iso9660.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/libarchive/archive_read_support_format_iso9660.c b/libarchive/archive_read_support_format_iso9660.c
index 28acfefbb..bad8f1dfe 100644
--- a/libarchive/archive_read_support_format_iso9660.c
+++ b/libarchive/archive_read_support_format_iso9660.c
@@ -2102,6 +2102,7 @@ parse_rockridge(struct archive_read *a, struct file_info *file,
const unsigned char *p, const unsigned char *end)
{
struct iso9660 *iso9660;
+ int entry_seen = 0;
iso9660 = (struct iso9660 *)(a->format->data);
@@ -2257,8 +2258,16 @@ parse_rockridge(struct archive_read *a, struct file_info *file,
}
p += p[2];
+ entry_seen = 1;
+ }
+
+ if (entry_seen)
+ return (ARCHIVE_OK);
+ else {
+ archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
+ "Tried to parse Rockridge extensions, but none found");
+ return (ARCHIVE_WARN);
}
- return (ARCHIVE_OK);
}
static int
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