[LogFS] Plug 8 byte information leak

Within each journal segment, 8 bytes at offset 24 would remain
uninitialized.

Signed-off-by: Joern Engel <joern@logfs.org>

diff --git a/fs/logfs/journal.c b/fs/logfs/journal.c
index 2c22a4ad5329e4531045c9b42a75de13d839382f..2957bfc21927862fcc643e273951f877ff625d2e 100644 (file)
--- a/fs/logfs/journal.c
+++ b/fs/logfs/journal.c
@@ -388,7 +388,10 @@ static void journal_get_erase_count(struct logfs_area *area)
 static int journal_erase_segment(struct logfs_area *area)
 {
        struct super_block *sb = area->a_sb;
-       struct logfs_segment_header sh;
+       union {
+               struct logfs_segment_header sh;
+               unsigned char c[ALIGN(sizeof(struct logfs_segment_header), 16)];
+       } u;
        u64 ofs;
        int err;
 
@@ -396,20 +399,21 @@ static int journal_erase_segment(struct logfs_area *area)
        if (err)
                return err;
 
-       sh.pad = 0;
-       sh.type = SEG_JOURNAL;
-       sh.level = 0;
-       sh.segno = cpu_to_be32(area->a_segno);
-       sh.ec = cpu_to_be32(area->a_erase_count);
-       sh.gec = cpu_to_be64(logfs_super(sb)->s_gec);
-       sh.crc = logfs_crc32(&sh, sizeof(sh), 4);
+       memset(&u, 0, sizeof(u));
+       u.sh.pad = 0;
+       u.sh.type = SEG_JOURNAL;
+       u.sh.level = 0;
+       u.sh.segno = cpu_to_be32(area->a_segno);
+       u.sh.ec = cpu_to_be32(area->a_erase_count);
+       u.sh.gec = cpu_to_be64(logfs_super(sb)->s_gec);
+       u.sh.crc = logfs_crc32(&u.sh, sizeof(u.sh), 4);
 
        /* This causes a bug in segment.c.  Not yet. */
        //logfs_set_segment_erased(sb, area->a_segno, area->a_erase_count, 0);
 
        ofs = dev_ofs(sb, area->a_segno, 0);
-       area->a_used_bytes = ALIGN(sizeof(sh), 16);
-       logfs_buf_write(area, ofs, &sh, sizeof(sh));
+       area->a_used_bytes = sizeof(u);
+       logfs_buf_write(area, ofs, &u, sizeof(u));
        return 0;
 }