jbd2: fix portability problems caused by unaligned accesses

This commit applies the e2fsck/recovery.c portions of commit
1e0c8ca7c08a ("e2fsck: fix portability problems caused by unaligned
accesses) from the e2fsprogs git tree.

The on-disk format for the ext4 journal can have unaigned 32-bit
integers.  This can happen when replaying a journal using a obsolete
checksum format (which was never popularly used, since the v3 format
replaced v2 while the metadata checksum feature was being stablized).

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

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index d47a0d96bf309767690c1290619eb913a3d64694..4c420926243799d5b6af0cb24340bc1f350ce9fd 100644 (file)
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -196,7 +196,7 @@ static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
 static int count_tags(journal_t *journal, struct buffer_head *bh)
 {
        char *                  tagp;
-       journal_block_tag_t *   tag;
+       journal_block_tag_t     tag;
        int                     nr = 0, size = journal->j_blocksize;
        int                     tag_bytes = journal_tag_bytes(journal);
 
@@ -206,14 +206,14 @@ static int count_tags(journal_t *journal, struct buffer_head *bh)
        tagp = &bh->b_data[sizeof(journal_header_t)];
 
        while ((tagp - bh->b_data + tag_bytes) <= size) {
-               tag = (journal_block_tag_t *) tagp;
+               memcpy(&tag, tagp, sizeof(tag));
 
                nr++;
                tagp += tag_bytes;
-               if (!(tag->t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
+               if (!(tag.t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
                        tagp += 16;
 
-               if (tag->t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
+               if (tag.t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
                        break;
        }
 
@@ -433,9 +433,9 @@ static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 }
 
 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
+                                     journal_block_tag3_t *tag3,
                                      void *buf, __u32 sequence)
 {
-       journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
        __u32 csum32;
        __be32 seq;
 
@@ -496,7 +496,7 @@ static int do_one_pass(journal_t *journal,
        while (1) {
                int                     flags;
                char *                  tagp;
-               journal_block_tag_t *   tag;
+               journal_block_tag_t     tag;
                struct buffer_head *    obh;
                struct buffer_head *    nbh;
 
@@ -613,8 +613,8 @@ static int do_one_pass(journal_t *journal,
                               <= journal->j_blocksize - descr_csum_size) {
                                unsigned long io_block;
 
-                               tag = (journal_block_tag_t *) tagp;
-                               flags = be16_to_cpu(tag->t_flags);
+                               memcpy(&tag, tagp, sizeof(tag));
+                               flags = be16_to_cpu(tag.t_flags);
 
                                io_block = next_log_block++;
                                wrap(journal, next_log_block);
@@ -632,7 +632,7 @@ static int do_one_pass(journal_t *journal,
 
                                        J_ASSERT(obh != NULL);
                                        blocknr = read_tag_block(journal,
-                                                                tag);
+                                                                &tag);
 
                                        /* If the block has been
                                         * revoked, then we're all done
@@ -647,8 +647,8 @@ static int do_one_pass(journal_t *journal,
 
                                        /* Look for block corruption */
                                        if (!jbd2_block_tag_csum_verify(
-                                               journal, tag, obh->b_data,
-                                               be32_to_cpu(tmp->h_sequence))) {
+                       journal, &tag, (journal_block_tag3_t *)tagp,
+                       obh->b_data, be32_to_cpu(tmp->h_sequence))) {
                                                brelse(obh);
                                                success = -EFSBADCRC;
                                                printk(KERN_ERR "JBD2: Invalid "