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From 7164a1c34d18831ac61c6744ad14ce916d389b3f Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Thu, 7 Jul 2016 14:22:41 +0200
Subject: [PATCH] libblkid: ignore extended partition at zero offset
If the extended partition starts at zero LBA then MBR is interpreted
as EBR and all is recursively parsed... result is out-of-memory.
MBR --extended-partition--> EBR --> MBR --> ENB --> MBR ...
Note that such PT is not possible to create by standard partitioning
tools.
Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1349536
Signed-off-by: Karel Zak <kzak@redhat.com>
Upstream-status: Backport
CVE: CVE-2016-5011 patch 1
Signed-off-by: Armin Kuster <akuster@mvista.com>
---
libblkid/src/partitions/dos.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/libblkid/src/partitions/dos.c b/libblkid/src/partitions/dos.c
index 9bba32f..e79f124 100644
--- a/libblkid/src/partitions/dos.c
+++ b/libblkid/src/partitions/dos.c
@@ -47,6 +47,12 @@ static int parse_dos_extended(blkid_probe pr, blkid_parttable tab,
int ct_nodata = 0; /* count ext.partitions without data partitions */
int i;
+ DBG(LOWPROBE, ul_debug("parse EBR [start=%d, size=%d]", ex_start/ssf, ex_size/ssf));
+ if (ex_start == 0) {
+ DBG(LOWPROBE, ul_debug("Bad offset in primary extended partition -- ignore"));
+ return 0;
+ }
+
while (1) {
struct dos_partition *p, *p0;
uint32_t start, size;
@@ -116,8 +122,12 @@ static int parse_dos_extended(blkid_probe pr, blkid_parttable tab,
start = dos_partition_get_start(p) * ssf;
size = dos_partition_get_size(p) * ssf;
- if (size && is_extended(p))
- break;
+ if (size && is_extended(p)) {
+ if (start == 0)
+ DBG(LOWPROBE, ul_debug("#%d: EBR link offset is zero -- ignore", i + 1));
+ else
+ break;
+ }
}
if (i == 4)
goto leave;
--
2.7.4
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