On Wed, Nov 30, 2011 at 08:22:39PM -0600, Dave Kleikamp wrote:
> On 11/30/2011 06:47 PM, Chris Dunlop wrote:
>>> It's also worth printing a message - this *is* a kernel bug of some
>>> description
>>> if it happens.
>>
>> Like the below? This covers the d_revalidate for 9p, afs, coda,
>> hfs, ncpfs, proc, sysfs.
>>
>> Note: jfs isn't susceptible to this problem, but the resolution
>> doesn't look like the other file systems, and from the comment
>> I'm not sure if the problem was really understood and if it's
>> doing the right thing:
>
> This code, as well as the comments, were copied from vfat. It seems
> reasonable for case-insensitive but case-preserving behavior (not jfs's
> default). The safe thing is to drop the negative dentry if we don't know
> the operation.
In that case, it looks like the thing to do might be to add the
"protection" to the start of jfs_ci_revaliate(), per how the
original has been changed in vfat:
fs/fat/namei_vfat.c:
static int vfat_revalidate_ci(struct dentry *dentry, struct nameidata *nd)
{
if (nd && nd->flags & LOOKUP_RCU)
return -ECHILD;
...
}
E.g.:
----------------------------------------------------------------------
Don't oops when abused by broken layered file systems
Signed-off-by: Chris Dunlop <[email protected]>
---
fs/jfs/namei.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/fs/jfs/namei.c b/fs/jfs/namei.c
index e17545e..5504f6e 100644
--- a/fs/jfs/namei.c
+++ b/fs/jfs/namei.c
@@ -1585,6 +1585,9 @@ out:
static int jfs_ci_revalidate(struct dentry *dentry, struct nameidata *nd)
{
+ if (nd && nd->flags & LOOKUP_RCU)
+ return -ECHILD;
+
/*
* This is not negative dentry. Always valid.
*
--
1.7.0.4
----------------------------------------------------------------------
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