[parted-devel] [PATCH 1/3] lib-fs-resize: Prevent crash resizing FAT16 file systems

[Mike Fleetwood]

Resizing FAT16 file system crashes in libparted/fs/r/fat/resize.c
create_resize_context() because it was dereferencing NULL pointer
fs_info->info_sector to copy the info_sector.

Only FAT32 file systems have info_sector populated by fat_open() ->
fat_info_sector_read().  FAT12 and FAT16 file systems don't have an
info_sector so pointer fs_info->info_sector remains assigned NULL from
fat_alloc().  When resizing a FAT file system create_resize_context()
was always dereferencing fs_info->info_sector to memory copy the
info_sector, hence it crashed for FAT12 and FAT16.

Make create_resize_context() only copy the info_sector for FAT32 file
systems.

Reported by Christian Hesse in
https://bugzilla.gnome.org/show_bug.cgi?id=735669
---
 NEWS                        |    4 ++++
 libparted/fs/r/fat/resize.c |   12 +++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/NEWS b/NEWS
index 297b0a5..da7db50 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,10 @@ GNU parted NEWS                                    -*- outline -*-
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Bug Fixes
+
+  libparted-fs-resize: Prevent crash resizing FAT16 file systems.
+
 
 * Noteworthy changes in release 3.2 (2014-07-28) [stable]
 
diff --git a/libparted/fs/r/fat/resize.c b/libparted/fs/r/fat/resize.c
index 919acf0..bfe60a0 100644
--- a/libparted/fs/r/fat/resize.c
+++ b/libparted/fs/r/fat/resize.c
@@ -668,11 +668,17 @@ create_resize_context (PedFileSystem* fs, const PedGeometry* new_geom)
 
 /* preserve boot code, etc. */
 	new_fs_info->boot_sector = ped_malloc (new_geom->dev->sector_size);
-	new_fs_info->info_sector = ped_malloc (new_geom->dev->sector_size);
 	memcpy (new_fs_info->boot_sector, fs_info->boot_sector,
 		new_geom->dev->sector_size);
-	memcpy (new_fs_info->info_sector, fs_info->info_sector,
-		new_geom->dev->sector_size);
+	new_fs_info->info_sector = NULL;
+	if (fs_info->fat_type == FAT_TYPE_FAT32)
+	{
+		PED_ASSERT (fs_info->info_sector != NULL);
+		new_fs_info->info_sector =
+			ped_malloc (new_geom->dev->sector_size);
+		memcpy (new_fs_info->info_sector, fs_info->info_sector,
+			new_geom->dev->sector_size);
+	}
 
 	new_fs_info->logical_sector_size = fs_info->logical_sector_size;
 	new_fs_info->sector_count = new_geom->length;
-- 
1.7.1