From: NeilBrown <neilb@suse.de>
Date: Fri, 15 Aug 2014 05:45:54 +0000 (+1000)
Subject: super1: don't allow adding a bitmap if there is no space.
X-Git-Tag: mdadm-3.3.2~3
X-Git-Url: http://git.ipfire.org/?p=thirdparty%2Fmdadm.git;a=commitdiff_plain;h=268cccac2e44e8e9166c9727e740d5d1f537b6a4

super1: don't allow adding a bitmap if there is no space.

If the data is too close to the superblock there may be
no space for a bitmap.
If that happens, fail the adding of the bitmap rather than
corrupt data.

Reported-by:  Lars Wijtemans <rhelbugzilla@lars.wijtemans.nl>
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=922944
---

diff --git a/super1.c b/super1.c
index 9834594c..02d6c7a1 100644
--- a/super1.c
+++ b/super1.c
@@ -2105,6 +2105,10 @@ add_internal_bitmap1(struct supertype *st,
 		/* Limit to 128K of bitmap when chunk size not requested */
 		room = 128*2;
 
+	if (room <= 1)
+		/* No room for a bitmap */
+		return 0;
+
 	max_bits = (room * 512 - sizeof(bitmap_super_t)) * 8;
 
 	min_chunk = 4096; /* sub-page chunks don't work yet.. */