Code: static bool ldm_frag_add (const u8 *data, int size, struct list_head *frags)
{
	struct frag *f;
	struct list_head *item;
	int rec, num, group;

	BUG_ON (!data || !frags);

	if (size < 2 * VBLK_SIZE_HEAD) {
		ldm_error("Value of size is to small.");
		return false;
	}

	group = get_unaligned_be32(data + 0x08);
	rec   = get_unaligned_be16(data + 0x0C);
	num   = get_unaligned_be16(data + 0x0E);
	if ((num < 1) || (num > 4)) {
		ldm_error ("A VBLK claims to have %d parts.", num);
		return false;
	}
	if (rec >= num) {
		ldm_error("REC value (%d) exceeds NUM value (%d)", rec, num);
		return false;
	}

	list_for_each (item, frags) {
		f = list_entry (item, struct frag, list);
		if (f->group == group)
			goto found;
	}

	f = kmalloc (sizeof (*f) + size*num, GFP_KERNEL);
	if (!f) {
		ldm_crit ("Out of memory.");
		return false;
	}

	f->group = group;
	f->num   = num;
	f->rec   = rec;
	f->map   = 0xFF << num;
 
 	list_add_tail (&f->list, frags);
 found:
 	if (f->map & (1 << rec)) {
 		ldm_error ("Duplicate VBLK, part %d.", rec);
 		f->map &= 0x7F;			/* Mark the group as broken */
		return false;
	}

	f->map |= (1 << rec);

	data += VBLK_SIZE_HEAD;
	size -= VBLK_SIZE_HEAD;

	memcpy (f->data+rec*(size-VBLK_SIZE_HEAD)+VBLK_SIZE_HEAD, data, size);

	return true;
}

Commit Message: Fix for buffer overflow in ldm_frag_add not sufficient

As Ben Hutchings discovered [1], the patch for CVE-2011-1017 (buffer
overflow in ldm_frag_add) is not sufficient.  The original patch in
commit c340b1d64000 ("fs/partitions/ldm.c: fix oops caused by corrupted
partition table") does not consider that, for subsequent fragments,
previously allocated memory is used.

[1] http://lkml.org/lkml/2011/5/6/407

Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Timo Warns <warns@pre-sense.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CWE ID: CWE-119
static bool ldm_frag_add (const u8 *data, int size, struct list_head *frags)
{
	struct frag *f;
	struct list_head *item;
	int rec, num, group;

	BUG_ON (!data || !frags);

	if (size < 2 * VBLK_SIZE_HEAD) {
		ldm_error("Value of size is to small.");
		return false;
	}

	group = get_unaligned_be32(data + 0x08);
	rec   = get_unaligned_be16(data + 0x0C);
	num   = get_unaligned_be16(data + 0x0E);
	if ((num < 1) || (num > 4)) {
		ldm_error ("A VBLK claims to have %d parts.", num);
		return false;
	}
	if (rec >= num) {
		ldm_error("REC value (%d) exceeds NUM value (%d)", rec, num);
		return false;
	}

	list_for_each (item, frags) {
		f = list_entry (item, struct frag, list);
		if (f->group == group)
			goto found;
	}

	f = kmalloc (sizeof (*f) + size*num, GFP_KERNEL);
	if (!f) {
		ldm_crit ("Out of memory.");
		return false;
	}

	f->group = group;
	f->num   = num;
	f->rec   = rec;
	f->map   = 0xFF << num;
 
 	list_add_tail (&f->list, frags);
 found:
	if (rec >= f->num) {
		ldm_error("REC value (%d) exceeds NUM value (%d)", rec, f->num);
		return false;
	}

 	if (f->map & (1 << rec)) {
 		ldm_error ("Duplicate VBLK, part %d.", rec);
 		f->map &= 0x7F;			/* Mark the group as broken */
		return false;
	}

	f->map |= (1 << rec);

	data += VBLK_SIZE_HEAD;
	size -= VBLK_SIZE_HEAD;

	memcpy (f->data+rec*(size-VBLK_SIZE_HEAD)+VBLK_SIZE_HEAD, data, size);

	return true;
}
