[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>

1 files changed, 14 insertions, 10 deletions

diff --git a/fs/logfs/journal.c b/fs/logfs/journal.c
index 2c22a4ad5329..2957bfc21927 100644
--- 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;
 }