vvfat: fat_chksum(): fix access above array bounds

Signed-off-by: Loïc Minier <loic.minier@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/vvfat.c

@@ -512,7 +512,7 @@ static inline uint8_t fat_chksum(const direntry_t* entry)
     for(i=0;i<11;i++) {
         unsigned char c;
 
-        c = (i <= 8) ? entry->name[i] : entry->extension[i-8];
+        c = (i < 8) ? entry->name[i] : entry->extension[i-8];
         chksum=(((chksum&0xfe)>>1)|((chksum&0x01)?0x80:0)) + c;
     }