The README file in the cramfs subdirectory says:
"All data is currently in host-endian format; neither mkcramfs nor the
kernel ever do swabbing."
If somebody tries to mount a cramfs with the wrong endianess,
cramfs only complains about a wrong magic but doesn't inform
the user that only the endianess isn't right.
The following patch adds an error message to the cramfs sources.
If a user tries to mount a cramfs with the wrong endianess using the
patched sources, cramfs will display the message "cramfs: wrong
endianess".
I'm currently not subscribed to the list, so please CC me for any comments.
Tested on an i386 box. Diffed against Linus' git-tree.
Signed-off-by: Andi Drebes <lists-receive@xxxxxxxxxxxxxxxxxxx>
---
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index 3d194a2..34c9b91 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -258,12 +258,21 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
/* Do sanity checks on the superblock */
if (super.magic != CRAMFS_MAGIC) {
+ /* check for wrong endianess */
+ if(super.magic == CRAMFS_MAGIC_WEND) {
+ if (!silent)
+ printk(KERN_ERR "cramfs: wrong endianess\n");
+ goto out;
+ }
+
/* check at 512 byte offset */
mutex_lock(&read_mutex);
memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
mutex_unlock(&read_mutex);
if (super.magic != CRAMFS_MAGIC) {
- if (!silent)
+ if(super.magic == CRAMFS_MAGIC_WEND && !silent)
+ printk(KERN_ERR "cramfs: wrong endianess\n");
+ else if (!silent)
printk(KERN_ERR "cramfs: wrong magic\n");
goto out;
}
diff --git a/include/linux/cramfs_fs.h b/include/linux/cramfs_fs.h
index 1dba681..3be4e5a 100644
--- a/include/linux/cramfs_fs.h
+++ b/include/linux/cramfs_fs.h
@@ -4,6 +4,7 @@
#include <linux/types.h>
#define CRAMFS_MAGIC 0x28cd3d45 /* some random number */
+#define CRAMFS_MAGIC_WEND 0x453dcd28 /* magic number with the wrong endianess */
#define CRAMFS_SIGNATURE "Compressed ROMFS"
/*
-
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