On Wednesday October 15, Trond.Myklebust@xxxxxxxxxx wrote:
> On Thu, 2008-10-16 at 09:28 +1100, Neil Brown wrote:
> > Hi Trond,
> > I wonder if you would consider including the following patch which
> > makes nfs_file_cred a little more robust.
> >
> > It isn't strictly needed with current mainline. However we have a patch
> > set which (among other things) passes a 'struct file' down (via
> > ATTR_FILE) for a chmod call.
> > If chmod is called on e.g. a device special file, this will cause
> > nfs3_proc_setattr to call nfs_file_cred on a 'struct file' which does
> > not have an associated open context or credential. That goes Oops.
> >
> > Thanks for your consideration,
> > NeilBrown
>
> Hi Neil,
>
> Won't this still end up exploding in nfs4_proc_setattr?
>
Yes, of course. I guess NFSv4 wasn't tested.
How's this?
Thanks,
NeilBrown
From: Neil Brown <neilb@xxxxxxxxxxxxxx>
Subject: [PATCH] Make nfs_file_cred more robust.
As not all files have an associated open_context (e.g. device special
files), it is safest to test for the existence of the open context
before de-referencing it.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
fs/nfs/nfs4proc.c | 6 ++++--
include/linux/nfs_fs.h | 8 ++++++--
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index c910413..83e700a 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1659,8 +1659,10 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
struct nfs_open_context *ctx;
ctx = nfs_file_open_context(sattr->ia_file);
- cred = ctx->cred;
- state = ctx->state;
+ if (ctx) {
+ cred = ctx->cred;
+ state = ctx->state;
+ }
}
status = nfs4_do_setattr(inode, cred, fattr, sattr, state);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 78a5922..63bf8f0 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -372,8 +372,12 @@ static inline struct nfs_open_context *nfs_file_open_context(struct file *filp)
static inline struct rpc_cred *nfs_file_cred(struct file *file)
{
- if (file != NULL)
- return nfs_file_open_context(file)->cred;
+ if (file != NULL) {
+ struct nfs_open_context *ctx =
+ nfs_file_open_context(file);
+ if (ctx)
+ return ctx->cred;
+ }
return NULL;
}
--
1.5.6.5
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