Fix palo to list all entries from the /boot directory

I noticed that palo randomly doesn't list all available files in
the /boot directory. This is caused by palo accessing non-aligned 32-bit
words and due to the absense of unalignment fixup routines wrong values
are returned for such words.

This is what happens:

The directory entry structure for ext2 is defined as:

struct ext2_dir_entry_2 {
        __u32   inode;                  /* Inode number */
        __u16   rec_len;                /* Directory entry length */
        __u8    name_len;               /* Name length */
        __u8    file_type;
        char    name[EXT2_NAME_LEN];    /* File name */

The inode member is of type __u32, so the compiler will access it with a 32-bit
load instruction.  The problem here is, that this __u32 might not be
word-aligned.  We are in the bootloader which doesn't has an
unalignment-handler, so depending on the CPU undefined values can be returned,
mostly often zero.

This patch fixes it by copying the directory entry to a naturally
aligned struct before accessing it with word accesses.

Fixes: 812b3b323186 ("Remove useless files from directory listing")
Signed-off-by: Helge Deller <deller@gmx.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/ipl/ext2.c b/ipl/ext2.c
index 8a96b9b..1b77c2d 100644
--- a/ipl/ext2.c
+++ b/ipl/ext2.c
@@ -209,8 +209,12 @@ static void swapino(struct ext2_inode *i)
 #endif
 }
 
-static void swapde(struct ext2_dir_entry_2 *de)
+static struct ext2_dir_entry_2 de_temp;
+static struct ext2_dir_entry_2 *swapde(struct ext2_dir_entry_2 *source)
 {
+    struct ext2_dir_entry_2 *de = &de_temp;
+
+    memcpy(de, source, sizeof(de_temp));
     if (Debug) printf("swapde: 0x%x 0x%x / ",
 				de->inode, de->rec_len);
     inplace(__le32_to_cpu, de->inode);
@@ -219,6 +223,7 @@ static void swapde(struct ext2_dir_entry_2 *de)
 				de->inode, de->rec_len,
 				de->name_len, de->file_type,
 				de->name_len, de->name);
+    return de;
 }
 
 static struct ext2_group_desc *ext2_gds(int i)
@@ -750,7 +755,7 @@ static struct ext2_dir_entry_2 *ext2_readdiri(struct ext2_inode *dir_inode,
 	}
 
 	dp = (struct ext2_dir_entry_2 *) (blkbuf + blockoffset);
-	swapde(dp);
+	dp = swapde(dp);
 	blockoffset += dp->rec_len;
 	/* ext2 deletes a file by zeroing its inode.  We skip deleted
 	 * files, corrupt entries and entries that aren't a regular