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SubjectRe: [PATCH] make cramfs look less hostile
On Sun, 15 June 2003 18:44:17 +0100, Christoph Hellwig wrote:
> On Sun, Jun 15, 2003 at 07:39:26PM +0200, Jörn Engel wrote:
> > > Umm, cramfs_fill_super has a silent parameter that's true for
> > > probing the root filesystem. I'd suggest disabling the printk
> > > completly if it's set.
> >
> > Good idea, but only at first glance. cramfs_fill_super() always gets
> > called with silent=1. So if "(!silent) printk(...);" is functionally
> > equivalent to ";".
>
> It's not. The rootfs is mounted with the (grossly misnamed) MS_VERBOSE
> flag which translates to the last argument of the fill_super callback
> set to 1.

Ok, you win this one. Leaves this case:
$ mount /dev/somewhere /mnt
cramfs: wrong magic
$ echo $?
0
$

Here I consider the message evil as well. The patch below on the
other hand might go a little too far. All the other printk()s are
rare and might hold some useful information for normal users as well.

Any arguments for or against this patch?

Jörn

--
To recognize individual spam features you have to try to get into the
mind of the spammer, and frankly I want to spend as little time inside
the minds of spammers as possible.
-- Paul Graham

--- linux-2.5.71/fs/cramfs/inode.c~cramfs_message 2003-06-05 17:47:36.000000000 +0200
+++ linux-2.5.71/fs/cramfs/inode.c 2003-06-15 19:39:03.000000000 +0200
@@ -27,6 +27,14 @@

#include <asm/uaccess.h>

+#define DEBUG 0 /* set to 1 for verbose messages during system bringup */
+
+#if DEBUG
+# define dprintk(fmt,args...) printk(fmt , ##args)
+#else
+# define dprintk(fmt,args...)
+#endif
+
static struct super_operations cramfs_ops;
static struct inode_operations cramfs_dir_inode_operations;
static struct file_operations cramfs_directory_operations;
@@ -218,20 +226,20 @@
/* check at 512 byte offset */
memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
if (super.magic != CRAMFS_MAGIC) {
- printk(KERN_ERR "cramfs: wrong magic\n");
+ dprintk(KERN_INFO "cramfs: magic not found\n");
goto out;
}
}

/* get feature flags first */
if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
- printk(KERN_ERR "cramfs: unsupported filesystem features\n");
+ dprintk(KERN_ERR "cramfs: unsupported filesystem features\n");
goto out;
}

/* Check that the root inode is in a sane state */
if (!S_ISDIR(super.root.mode)) {
- printk(KERN_ERR "cramfs: root is not a directory\n");
+ dprintk(KERN_ERR "cramfs: root is not a directory\n");
goto out;
}
root_offset = super.root.offset << 2;
@@ -247,12 +255,12 @@
sbi->magic=super.magic;
sbi->flags=super.flags;
if (root_offset == 0)
- printk(KERN_INFO "cramfs: empty filesystem");
+ dprintk(KERN_INFO "cramfs: empty filesystem");
else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
((root_offset != sizeof(struct cramfs_super)) &&
(root_offset != 512 + sizeof(struct cramfs_super))))
{
- printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
+ dprintk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
goto out;
}

-
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