[syslinux:master] chain.c32: Handle nonlinear logical partitions

[syslinux-bot for H. Peter Anvin]

Commit-ID:  1b07af66b1632a5ae269770015583d1b8d48deed
Gitweb:     http://syslinux.zytor.com/commit/1b07af66b1632a5ae269770015583d1b8d48deed
Author:     H. Peter Anvin <hpa at zytor.com>
AuthorDate: Wed, 27 Jan 2010 15:45:01 -0800
Committer:  H. Peter Anvin <hpa at zytor.com>
CommitDate: Wed, 27 Jan 2010 15:45:01 -0800

chain.c32: Handle nonlinear logical partitions

Some partitioning program, including at least parted, apparently
create the list of logical partition headers nonlinearly with the
partition themselves.  Thus, make it a requirement that then fit
inside the overall extended partition, but not inside the
corresponding sublogical partition.

Reported-by: Gert Huselmans <gerth at zytor.com>
Signed-off-by: H. Peter Anvin <hpa at zytor.com>


---
 com32/modules/chain.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/com32/modules/chain.c b/com32/modules/chain.c
index 2dd8074..458ea89 100644
--- a/com32/modules/chain.c
+++ b/com32/modules/chain.c
@@ -1,7 +1,7 @@
 /* ----------------------------------------------------------------------- *
  *
  *   Copyright 2003-2009 H. Peter Anvin - All Rights Reserved
- *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
+ *   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -394,10 +394,13 @@ static struct part_entry *find_logical_partition(int whichpart, char *table,
 	    /* Adjust the offset to account for the extended partition itself */
 	    ptab[i].start_lba += self->start_lba;
 
-	    /* Sanity check entry: must not extend outside the extended partition.
-	       This is necessary since some OSes put crap in some entries. */
-	    if (ptab[i].start_lba + ptab[i].length <= self->start_lba ||
-		ptab[i].start_lba >= self->start_lba + self->length)
+	    /*
+	     * Sanity check entry: must not extend outside the
+	     * extended partition.  This is necessary since some OSes
+	     * put crap in some entries.  Note that root is non-NULL here.
+	     */
+	    if (ptab[i].start_lba + ptab[i].length <= root->start_lba ||
+		ptab[i].start_lba >= root->start_lba + root->length)
 		continue;
 
 	    /* OK, it's a data partition.  Is it the one we're looking for? */