From 7164a1c34d18831ac61c6744ad14ce916d389b3f Mon Sep 17 00:00:00 2001 From: Karel Zak 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 Upstream-status: Backport CVE: CVE-2016-5011 patch 1 Signed-off-by: Armin Kuster --- 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