blkid: more sanity checks for swap v1

mkswap followed by pvcreate on a block device
will still turn up as "swap" in blkid, because
pvcreate isn't particularly careful about zeroing
old signatures.  (neither is mkswap, for that matter).

Testing for appropriate version and page counts
gives us a bit more confidence that we have a
real swap (v1) partition.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/blkid/probe.c b/lib/blkid/probe.c
index 45885c390746698fd8dfa35b624c12ab45047805..4347ae1f725fac047dfaf2f7199bb2fcad542157 100644 (file)
--- a/lib/blkid/probe.c
+++ b/lib/blkid/probe.c
@@ -827,7 +827,7 @@ static int probe_swap0(struct blkid_probe *probe,
 }
 
 static int probe_swap1(struct blkid_probe *probe,
-                      struct blkid_magic *id __BLKID_ATTR((unused)),
+                      struct blkid_magic *id,
                       unsigned char *buf __BLKID_ATTR((unused)))
 {
        struct swap_id_block *sws;
@@ -843,6 +843,12 @@ static int probe_swap1(struct blkid_probe *probe,
        if (!sws)
                return 1;
 
+       /* check for wrong version or zeroed pagecount, for sanity */
+       if (!memcmp(id->bim_magic, "SWAPSPACE2", id->bim_len) &&
+                       (blkid_le32(sws->sws_version) != 1 ||
+                        sws->sws_lastpage == 0))
+               return 1;
+
        /* arbitrary sanity check.. is there any garbage down there? */
        if (sws->sws_pad[32] == 0 && sws->sws_pad[33] == 0)  {
                if (sws->sws_volume[0])