blkid: avoid FPE crash when probing a HFS+ superblock with a zero blocksize

This problem was reported by Adam Buchbinder.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/blkid/probe.c b/lib/blkid/probe.c
index 865d9aa..283ee0a 100644 (file)
--- a/lib/blkid/probe.c
+++ b/lib/blkid/probe.c
@@ -1184,6 +1184,8 @@ static int probe_hfs(struct blkid_probe *probe __BLKID_ATTR((unused)),
 }
 
 
+#define HFSPLUS_SECTOR_SIZE        512
+
 static int probe_hfsplus(struct blkid_probe *probe,
                         struct blkid_magic *id,
                         unsigned char *buf)
@@ -1247,6 +1249,9 @@ static int probe_hfsplus(struct blkid_probe *probe,
        }
 
        blocksize = blkid_be32(hfsplus->blocksize);
+       if (blocksize < HFSPLUS_SECTOR_SIZE)
+               return 1;
+
        memcpy(extents, hfsplus->cat_file.extents, sizeof(extents));
        cat_block = blkid_be32(extents[0].start_block);